Add type_name function to query the type of a value

doc/function/index.txt

@@ -11,6 +11,7 @@ These functions are built into the program, other [[type:function]]s can be defi
 | [[fun:to_color]]		Convert any value to a [[type:color]]
 | [[fun:to_image]]		Convert any value to an [[type:image]]
 | [[fun:to_date]]		Convert any value to a [[type:date]]
+| [[fun:type_name]]		Get the type of a value
 	
 ! Numbers			<<<
 | [[fun:abs]]			Absolute value

doc/function/type_name.txt

@@ -0,0 +1,17 @@
+Function: type_name
+
+DOC_MSE_VERSION: since 2.0.2
+
+--Usage--
+> type_name(any_value)
+
+Return the type of the given value as a string.
+Note that type names are localized, so they should not be compared to a fixed string.
+
+--Parameters--
+! Parameter	Type			Description
+| @input@	''any type''		Value to determine the type of.
+
+--Examples--
+> type_name("hello") == "string"
+> type_name(1)       == "integer number"