V1.2 Released

Added a lot of features:
- Timer.getAvaliable(); // Returns one avaliable timer, not being used
- getPeriod(), getFrequency(); // Returns current timer frequency or period
- detachInterrupt(); // Removes callback, and leave timer avaliable for "getAvaliable()"
- Added new example, using getAvaliable() with 9 timers at the same time
- BIG Improvement on clock reliability. Now, the best clock is selected upon your choosen frequency/period.