POC: dynamically adding all fonts to ComplexOption items

Good news: I did succed in being able to populate the ComplexOption with a list of OptionItems for every font found on the system.

Bad news: It crashed my system.

Most of these fonts are probably useless anyway. For example, I randomly picked-one and it was a font for the Tamil language. We need a way to par-down the list to be shorter.

TODO:
 1. remove symlinks (duplicates) from the list of fonts
 2. remove fonts that don't have glyphs for latin characters

For #2, I found some code on SE that uses the python module fonttools, but I actually liked this one better -- as it just uses the built-in module unicodedata

 * https://superuser.com/questions/876572/how-do-i-find-out-which-font-contains-a-certain-special-character

For more info, see:

 * #55 (comment)

src/buskill_gui.py

@@ -686,9 +686,21 @@ def _choose_settings_screen(self, instance):
 				option_item = BusKillOptionItem( self.key, value, desc, confirmation, icon, self, manager )
 				setting_screen.content.add_widget( option_item )
 
-			# TODO: change this to actually add fonts that are available
-			option_item = BusKillOptionItem( 'key', 'some_font', 'desc', '', '', self, manager )
-			setting_screen.content.add_widget( option_item )
+			# handle the "font" option
+			if self.key == 'font':
+				# first we must determine what fonts are available on this system
+
+				font_paths = []
+				for fonts_dir_path in LabelBase.get_system_fonts_dir():
+
+					for root, dirs, files in os.walk(fonts_dir_path):
+						for file in files:
+							if file.lower().endswith(".ttf"):
+								font_path = str(os.path.join(root, file))
+								font_paths.append( font_path )
+								option_item = BusKillOptionItem( self.key, font_path, 'desc', '', '', self, manager )
+
+								setting_screen.content.add_widget( option_item )
 
 			# add the new ComplexOption sub-screen to the Screen Manager
 			manager.add_widget( setting_screen )

src/packages/buskill/settings_buskill.json

@@ -21,13 +21,5 @@
 		"options": ["roboto"],
 		"options_long": ["Roboto Font"],
 		"options_icons": ["\ue1bf","\ue62a"]
-	},
-	{
-		"type": "options",
-		"title": "Font",
-		"desc": "Choose the font in the app",
-		"section": "buskill",
-		"key": "font",
-		"options": ["font1", "font2"]
 	}
 ]