controls.txt and options UI

very scuffed, OptionsMenu.hx is now mostly copied from FreeplayState.hx with no actual functionality
currently it reads lines off of controls.txt and displays them on Options menu which is now accessible from main menu
controls.txt has control functions prefixed with "set", IE "setUP", then the corresponding key on the following line IE "W"

assets/data/controls.txt

@@ -0,0 +1,32 @@
+setUP
+W
+setUP (ALTERNATE)
+FlxKey.UP
+setDOWN
+S
+setDOWN (ALTERNATE)
+FlxKey.DOWN
+setLEFT
+A
+setLEFT (ALTERNATE)
+FlxKey.LEFT
+setRIGHT
+D
+setRIGHT (ALTERNATE)
+FlxKey.RIGHT
+setACCEPT
+Z
+setACCEPT (ALTERNATE)
+ENTER
+setBACK
+BACKSPACE
+setBACK (ALTERNATE)
+ESCAPE
+setPAUSE
+P
+setPAUSE (ALTERNATE)
+ENTER
+setRESET
+R
+setRESET (ALTERNATE)
+null