Enable cursor functionality for InputText

[DigiEggz]

Allows FlxUICursor to function with FlxUIInputText widgets.

[Geokureli]

can you share a little test project that showcases what this change does?

[DigiEggz]

I'm considering adding a bit more functionality to this. The plan is for TextFields to properly interact with the floating FlxUICursors. As it stands, UI cursors cannot interact with text fields in any way.

Edit: I ended up using a cursor reference within InputText fields. It's used to set the FlxUICursor's active flag when set_hasFocus changes. I've implemented it in my own project, but not sure of the best course of action for a general library change.