Card data in images (minimum viable)

* remove wxEmptyString

* improve style tab carousel

* create web request window

* add drop target and drop source

src/data/field.cpp

@@ -113,14 +113,9 @@ Style::Style(const FieldP& field)
   , visible(true)
   , automatic_side(AUTO_UNKNOWN)
   , content_dependent(false)
-{
-  field->styleP = this;
-}
+{}
 
-Style::~Style()
-{
-  fieldP->styleP = nullptr;
-}
+Style::~Style() {}
 
 IMPLEMENT_REFLECTION(Style) {
   REFLECT(z_index);
@@ -138,7 +133,6 @@ IMPLEMENT_REFLECTION(Style) {
 
 void init_object(const FieldP& field, StyleP& style) {
   if (!style) style = field->newStyle();
-  field->styleP = style;
 }
 template <> StyleP read_new<Style>(Reader&) {
   throw InternalError(_("IndexMap contains nullptr StyleP the application should have crashed already"));
@@ -268,18 +262,6 @@ void mark_dependency_member(const Style& style, const String& name, const Depend
   style.markDependencyMember(name,dep);
 }
 
-String Style::getRect() {
-  return _("---") +
-         wxString::Format(wxT("%i"), (int)(left)) +
-         _("-") +
-         wxString::Format(wxT("%i"), (int)(top)) +
-         _("-") +
-         wxString::Format(wxT("%i"), (int)(width)) +
-         _("-") +
-         wxString::Format(wxT("%i"), (int)(height)) +
-         _("---");
-}
-
 // ----------------------------------------------------------------------------- : StyleListener
 
 void Style::addListener(StyleListener* listener) {