Editor tile converter "author" field

Adds an "author" field for the "data.stcd" file, which allows specifying a converter's author.

Additionally renames the "0.5.x Crystal Tiles" converter to "Pre-0.6.3 Crystal Tiles" for better accuracy.

data/images/converters/data.stcd

@@ -1,10 +1,12 @@
 (supertux-converter-data
   (nightly_all_tiles.sttc
     (title (_ "Nightly Tiles"))
-    (description (_ "Levels, created in previous Nightly builds, have their tiles broken. Use this converter to restore all tiles in the level to their proper state!"))
+    (author "SuperTux Team")
+    (description (_ "For levels, created in previous Nightly builds."))
   )
-  (051_crystal_tiles.sttc
-    (title (_ "0.5.x Crystal Tiles"))
-    (description (_ "Levels, created in pre-0.6.3 versions, which use crystal tiles, have their crystal tiles broken. Use this converter to restore all crystal tiles in the level to their proper state!"))
+  (pre-0.6.3_crystal_tiles.sttc
+    (title (_ "Pre-0.6.3 Crystal Tiles"))
+    (author "tylerandari12")
+    (description (_ "For levels, created in pre-0.6.3 versions, which use crystal tiles."))
   )
 )

src/supertux/menu/editor_converters_menu.cpp

@@ -16,6 +16,8 @@
 
 #include "supertux/menu/editor_converters_menu.hpp"
 
+#include <fmt/format.h>
+
 #include "editor/editor.hpp"
 #include "gui/dialog.hpp"
 #include "gui/item_action.hpp"
@@ -44,6 +46,7 @@ EditorConvertersMenu::EditorConvertersMenu() :
 
       auto mapping = iter.as_mapping();
       mapping.get("title", converter.title);
+      mapping.get("author", converter.author);
       mapping.get("description", converter.description);
 
       m_converters.insert({ iter.get_key(), std::move(converter) });
@@ -65,7 +68,8 @@ EditorConvertersMenu::EditorConvertersMenu() :
                return;
 
              item.set_text("\"" + it->second.title + "\"");
-             item.set_help(it->second.description);
+             item.set_help(it->second.description + (it->second.author.empty() ? "" :
+                           "\n \n" + fmt::format(fmt::runtime(_("By: {}")), it->second.author)));
            });
 
   add_entry(MNID_CONVERT_TILES, _("Convert Tiles By File"))

src/supertux/menu/editor_converters_menu.hpp

@@ -35,9 +35,12 @@ class EditorConvertersMenu final : public Menu
 
   struct Converter
   {
-    Converter() : title(), description() {}
+    Converter() :
+      title(), author(), description()
+    {}
 
     std::string title;
+    std::string author;
     std::string description;
   };