- Implemented support for fixed process on timer. Useful for cooldowns without the influence from framerate

similar to animation player (idle/fixed mode), where idle mode = old timer, fixed mode = fixed process implementation:
Example of the behaviour with a stream of bullets with timers on different frame rates:
https://gfycat.com/HeartyImpressiveIndiancow

- A change for more uniform ticks on fixed/idle

without this fix:
http://i.imgur.com/0TMQ6CG.png
with this fix:
http://i.imgur.com/3zYx16c.png

scene/main/timer.h

@@ -46,6 +46,11 @@ protected:
 	static void _bind_methods();
 public:
 
+	enum TimerProcessMode {
+		TIMER_PROCESS_FIXED,
+		TIMER_PROCESS_IDLE,
+	};
+
 	void set_wait_time(float p_time);
 	float get_wait_time() const;
 
@@ -60,7 +65,16 @@ public:
 
 	float get_time_left() const;
 
+	void set_timer_process_mode(TimerProcessMode p_mode);
+	TimerProcessMode get_timer_process_mode() const;
 	Timer();
+
+private:
+	TimerProcessMode timer_process_mode;
+	void _set_process(bool p_process, bool p_force = false);
+
 };
 
+VARIANT_ENUM_CAST(Timer::TimerProcessMode);
+
 #endif // TIMER_H