Peeking at Espruino Board Timers 2, 3, 4, and 5

Thanks for the feedback Gordon. It may be a bit premature for a module as there are other examples in the documentation to work through and a need to make the code a bit more generalized. For example the previous code that measures frequency may be more accurate if two timers are chained together, where one does the counting and the other does the time base gating of the first.