Add Angle Getter

[CobaltBar]

adds a blank getter to angle in FlxObject for other classes to override.
This could be used for an angle offset, for instance.

[Geokureli]

tbh i'm not a fan of these getter/setters and the complexity and obfuscation they cause, I'm trying to move away from them. Simply add a getSpecialAngle function to your FlxObject/sprite extending class and use that instead

[CobaltBar]

I was trying to avoid using a custom variable, so i wrote a macro to add a getter for angle in my use case.
I thought this might be useful in case someone else needed to use get_angle

Should I close the PR? (I have no idea how to respond to this)

[Geokureli]

I was gonna close, but thought i'd wait for a response in case you had a compelling counter-argument. The effort is appreciated, but yeah, I think extension is a better route