add keyboard input

src/flixel/FlxG.hx

@@ -1,5 +1,6 @@
 package flixel;
 
+import flixel.input.FlxKeyManager;
 import raylib.Raylib;
 import flixel.system.FlxMemory;
 import flixel.FlxCamera;
@@ -30,6 +31,8 @@ class FlxG {
 
 	public static var sound(default, null):SoundFrontEnd = new SoundFrontEnd();
 
+	public static var keys(default, null):FlxKeyManager;
+
 	public static function switchState(nextState:FlxState):Void {
 		cameras.reset();
 		sound.destroy(true);
@@ -57,6 +60,8 @@ class FlxG {
 		initialWidth = width;
 		initialHeight = height;
 		cameras.reset();
+
+		keys = new FlxKeyManager();
 	}
 
 	@:noCompletion

src/flixel/input/FlxBaseKeyList.hx

@@ -0,0 +1,26 @@
+package flixel.input;
+
+import raylib.KeyboardKey;
+
+class FlxBaseKeyList {
+
+    public var state(default, null):FlxInputState;
+
+    public function new(state:FlxInputState) {
+        this.state = state;
+    }
+
+    public function check(key:KeyboardKey):Bool {
+        switch (this.state) {
+            case JUST_RELEASED:
+                return isKeyReleased(key);
+            case RELEASED:
+                return !isKeyDown(key);
+            case PRESSED:
+                return isKeyDown(key);
+            case JUST_PRESSED:
+                return isKeyPressed(key);
+        }
+        return false;
+    }
+}

src/flixel/input/FlxInputState.hx

@@ -0,0 +1,8 @@
+package flixel.input;
+
+enum abstract FlxInputState(Int) from Int {
+	var JUST_RELEASED:Int = -1;
+	var RELEASED:Int = 0;
+	var PRESSED:Int = 1;
+	var JUST_PRESSED:Int = 2;
+}

src/flixel/input/FlxKeyManager.hx

@@ -0,0 +1,20 @@
+package flixel.input;
+
+import flixel.input.keyboard.FlxKeyList;
+
+class FlxKeyManager {
+	public var pressed(default, null):FlxKeyList;
+
+	public var justPressed(default, null):FlxKeyList;
+
+	public var released(default, null):FlxKeyList;
+
+	public var justReleased(default, null):FlxKeyList;
+
+	public function new() {
+        pressed = new FlxKeyList(PRESSED);
+        justPressed = new FlxKeyList(JUST_PRESSED);
+        released = new FlxKeyList(RELEASED);
+        justReleased = new FlxKeyList(JUST_RELEASED);
+    }
+}