Fix and Additions to Timer Example

[iledesma08]

• Fixed main Timer example: the way it was, it caused the Timer to reset each time the match 0 related to LED0 was reached, avoiding toggle of other LEDs. The solution wasnt as simple as making the Timer reset when the match of LED3 is reached, because that would have forced all LEDs to have the same frequency. Instead, trying to stay aligned to the original example, a counter system was implemented, but the disadvantage of this is that it forces us to make all LEDs share a base frequency.
• Added alternative Timer example: this aims to be what the original example tried to do. Different timers are asigned to the 4 original LEDs, giving us the versatility to let all LEDs have different frequencies and not shared ones. Also, the toggling process is now automatic through Timer features instead of being programmed through the Timer interruption handler.

[GabrielEValenzuela]

@iledesma08 Please add alternative following the same structure that above examples, let's keep one project for example :)