Removed deprecated classes

• FlxRayCastTilemap: FlxBaseTilemap has an all-around better ray() method (#455)
• FlxMouseControl: Use FlxMouseEvent, instead (#455)

Changes and improvements:

• Documentation: Various mprovements
  • FlxGlitchEffect, FlxWaveEffect and FlxRainbowEffect (#457)
  • FlxTypeText (#467)
    (#469)
• Remove deprecation warnings for compatibility with Flixel 6.1.2 (#471)
  • FlxPoint: Removed deprecated addPoint, subtractPoint and the like
  • FlxColor: Replaced deprecated to24Bit with rgb
  • FlxSprite: Removed refs to useColorTransform on new flixel versions >= 6.1.0
• FlxButtonPlus: Deprecated, but not removed, use FlxButton, instead (#472)
• FlxButtonPlus: Add get_text setter to fix reported CI issues (#472)

Bugfixes:

• FlxSlider: Fix hitbox when using secondary cameras (#458)
• FlxGridOverlay: Prevent freeze when passing invalid cell size values (#462)