Major input handling improvements (#28):

- Support joystick hotplugging
- Support axes as buttons (means xbox360 shoulder triggers can be used as buttons)
- Show pretty joystick axis & button names if possible
- Tabify input actions UI
- Add 'mouse' column to input actions UI
- Allow to configure form hotkeys
- Allow ALL keys, get rid of internal key remapping
- SDL2: Use scancodes instead of keycodes since they are layout independent
- Allow extra mouse buttons (if present)
- Remove "lmbd" & "lmbu" actions in favor of "PrimaryAction" & "SecondaryAction"
  Makes the configuration less redundant and doesn't send each action twice,
  which happened if both were set to the same key.
- Fix Regressions from prev commits (menu not opening on Esc)

Still has a few minor bugs/issues that need to be fixed,
but pushing this now before the commit gets too large again.

BBGE/Joystick.h

@@ -13,6 +13,8 @@
 #define MAX_JOYSTICK_BTN 32
 #define MAX_JOYSTICK_AXIS 32
 
+const static float JOY_AXIS_THRESHOLD = 0.6f;
+
 class Joystick
 {
 public:
@@ -32,20 +34,28 @@ public:
 	void calibrate(Vector &vec, float dead);
 	bool anyButton() const;
 	bool getButton(unsigned id) const { return !!(buttonBitmask & (1u << id)); }
+	float getAxisUncalibrated(int id) const;
+	int getNumAxes() const;
 	int getIndex() const { return stickIndex; }
 	int getInstanceID() const { return instanceID; }
 	inline bool isEnabled() const { return enabled; }
 
+	const char *getAxisName(int axis) const;
+	const char *getButtonName(int btn) const;
+
 	Vector rightStick;
 
 	int s1ax, s1ay, s2ax, s2ay;
 
 private:
+	void clearAxes();
 	bool enabled;
 	int stickIndex;
 	int instanceID;
-	unsigned buttonBitmask; // FIXME: this should go
+	unsigned buttonBitmask;
+	int numJoyAxes;
 	SDL_Joystick *sdl_joy;
+	float axisRaw[MAX_JOYSTICK_AXIS];
 
 #  ifdef BBGE_BUILD_SDL2
 	SDL_GameController *sdl_controller;