5.1.0

• Rebuilds __input_config_icons() to use a fluent interface. This works around two particularly nasty bugs in GameMaker that have gone unaddressed for at least 6 weeks (#371 #410) and we got bored of waiting
• Adds imported data verification functions: input_system_verify(), input_player_verify(), and input_profile_verify()
• Fixes empty bindings having no label, leading to invalid return values downstream
• Fixes crash when importing bindings that contain attached gamepad description data