Add some more preparation for multi-font support and proper unloading

find_font_by_name() just finds the index of a given font name. This
index is supposed to be stored and reused, because the font (for a
language/level) won't be changed very often. So this function would
only run when getting the language metadata, when loading a level, etc.

desktop_version/src/Font.h

@@ -52,6 +52,8 @@ struct GlyphInfo
 
 struct Font
 {
+    char name[64];
+
     uint8_t glyph_w;
     uint8_t glyph_h;