add set_metadata, get_metadata script functions

doc/function/from_json.txt

@@ -10,7 +10,7 @@ To see the required syntax, use an output of the [[fun:to_json]] function.
 --Parameters--
 ! Parameter	Type				Description
 | @input@	[[type:string]]		JSON string to convert to an MSE script value.
-| @set@		[[type:set]]		The active set. This can be omited since "set" is a predefined variable.
+| @set@		[[type:set]]		The active set. This can be omitted since "set" is a predefined variable.
 
 --Examples--
 > add_card_to_set(from_json("\{\"mse_object_type\":\"card\", \"data\":\{\"name\":\"Ajani\", \"rarity\":\"mythic rare\"\}\}"))

doc/function/get_back_face.txt

@@ -9,4 +9,4 @@ Returns nil if no link of type "Back Face", or no card was found.
 --Parameters--
 ! Parameter	Type				Description
 | @input@	[[type:card]]		The card whose links we'll inspect.
-| @set@		[[type:set]]		The set in which to look. This can be omited since 'set' is a predefined variable.
+| @set@		[[type:set]]		The set in which to look. This can be omitted since 'set' is a predefined variable.

doc/function/get_card_export_settings.txt

@@ -10,4 +10,4 @@ Returns and array whose first element is the zoom percentage, the second is the
 --Parameters--
 ! Parameter	Type					Description
 | @input@	[[type:card]]		The card you want to retrieve the export settings from.
-| @set@		[[type:set]]		The set the card belongs to. This can be omited since "set" is a predefined variable.
+| @set@		[[type:set]]		The set the card belongs to. This can be omitted since "set" is a predefined variable.

doc/function/get_card_from_uid.txt

@@ -9,4 +9,4 @@ Returns nil if no card was found.
 --Parameters--
 ! Parameter	Type				Description
 | @input@	[[type:string]]		The uid of the card we want to retrieve.
-| @set@		[[type:set]]		The set in which to look. This can be omited since 'set' is a predefined variable.
+| @set@		[[type:set]]		The set in which to look. This can be omitted since 'set' is a predefined variable.

doc/function/get_card_stylesheet.txt

@@ -10,7 +10,7 @@ This is for use in exporter scripts. In card scripts, use the "stylesheet" prede
 --Parameters--
 ! Parameter	Type					Description
 | @input@	[[type:card]]		The card you want to retrieve the stylesheet from.
-| @set@		[[type:set]]		The set the card belongs to. In an exporter script, this can be omited since "set" is a predefined variable.
+| @set@		[[type:set]]		The set the card belongs to. In an exporter script, this can be omitted since "set" is a predefined variable.
 
 --Examples--
 > # Retrieve the card regions from the card's stylesheet

doc/function/get_card_styling.txt

@@ -10,7 +10,7 @@ This is for use in exporter scripts. In card scripts, use the 'styling' predefin
 --Parameters--
 ! Parameter	Type					Description
 | @input@	[[type:card]]		The card you want to retrieve the styling data from.
-| @set@		[[type:set]]		The set the card belongs to. In an exporter script, this can be omited since 'set' is a predefined variable.
+| @set@		[[type:set]]		The set the card belongs to. In an exporter script, this can be omitted since 'set' is a predefined variable.
 
 --Examples--
 > # Retrieve the value "is foil" from the card's styling options

doc/function/get_front_face.txt

@@ -9,4 +9,4 @@ Returns nil if no link of type "Front Face", or no card was found.
 --Parameters--
 ! Parameter	Type				Description
 | @input@	[[type:card]]		The card whose links we'll inspect.
-| @set@		[[type:set]]		The set in which to look. This can be omited since 'set' is a predefined variable.
+| @set@		[[type:set]]		The set in which to look. This can be omitted since 'set' is a predefined variable.

doc/function/get_metadata.txt

@@ -0,0 +1,15 @@
+Function: get_metadata
+
+--Usage--
+> get_metadata(input: image)
+
+Returns the metadata of an image, or an empty string if there isn't any.
+
+Metadata is only stored when an image is saved as a PNG.
+It is saved in a uncompressed iTXt chunk with the key "Description".
+If the image is saved as a JPG, the metadata is lost.
+
+--Parameters--
+! Parameter	Type				Description
+| @input@	[[type:image]]		The image whose metadata we'll get.
+| @set@		[[type:set]]		The active set. This can be omitted since 'set' is a predefined variable.

doc/function/set_metadata.txt

@@ -0,0 +1,16 @@
+Function: set_metadata
+
+--Usage--
+> set_metadata(input: image, metadata: string)
+
+Returns a copy of the input image with the metadata set to the given string.
+
+Metadata is only stored when an image is saved as a PNG.
+It is saved in a uncompressed iTXt chunk with the key "Description".
+If the image is saved as a JPG, the metadata is lost.
+
+--Parameters--
+! Parameter	Type				Description
+| @input@	[[type:image]]		The image that will be copied.
+| @metadata@	[[type:string]]		The metadata that will be stored in the copy.
+| @set@		[[type:set]]		The active set. This can be omitted since 'set' is a predefined variable.

doc/function/to_json.txt

@@ -3,13 +3,14 @@ Function: to_json
 --Usage--
 > to_json(some_script_value)
 
-Convert a [[type:list]], a [[type:map]], a [[type:card]], a [[type:keyword]], a [[type:pack_type]] or a [[type:set]] to a JSON string.
+Convert a [[type:list]], a [[type:map]], a [[type:style]], a [[type:card]], a [[type:keyword]], a [[type:pack_type]] or a [[type:set]] to a JSON string.
 
+This method is also useful for debugging purposes.
 
 --Parameters--
 ! Parameter	Type				Description
 | @input@	some_script_value		MSE script value to convert to a JSON string.
-| @set@		[[type:set]]		The active set. This can be omited since "set" is a predefined variable.
+| @set@		[[type:set]]		The active set. This can be omitted since "set" is a predefined variable.
 
 --Examples--
 > to_json(card)

src/script/functions/image.cpp

@@ -65,6 +65,22 @@ SCRIPT_FUNCTION(download_image) {
 
 // ----------------------------------------------------------------------------- : Image functions
 
+SCRIPT_FUNCTION(get_metadata) {
+  SCRIPT_PARAM(Set*, set);
+  SCRIPT_PARAM(GeneratedImageP, input);
+  Image img = input->generate(GeneratedImage::Options(0, 0, set));
+  SCRIPT_RETURN(img.GetOption(wxIMAGE_OPTION_PNG_DESCRIPTION));
+}
+
+SCRIPT_FUNCTION(set_metadata) {
+  SCRIPT_PARAM(Set*, set);
+  SCRIPT_PARAM(GeneratedImageP, input);
+  SCRIPT_PARAM(String, metadata);
+  Image img = input->generate(GeneratedImage::Options(0, 0, set));
+  img.SetOption(wxIMAGE_OPTION_PNG_DESCRIPTION, metadata);
+  return make_intrusive<ArbitraryImage>(img);
+}
+
 SCRIPT_FUNCTION(width_of) {
   SCRIPT_PARAM(Set*, set);
   SCRIPT_PARAM(GeneratedImageP, input);
@@ -311,6 +327,8 @@ SCRIPT_FUNCTION(built_in_image) {
 void init_script_image_functions(Context& ctx) {
   ctx.setVariable(_("to_image"),         script_to_image);
   ctx.setVariable(_("to_card_image"),    script_to_card_image);
+  ctx.setVariable(_("set_metadata"),     script_set_metadata);
+  ctx.setVariable(_("get_metadata"),     script_get_metadata);
   ctx.setVariable(_("width_of"),         script_width_of);
   ctx.setVariable(_("height_of"),        script_height_of);
   ctx.setVariable(_("dimensions_of"),    script_dimensions_of);