add timer.starta and timer.stopa to stop and start a systimer that calls a bitlash function

[jacobrosenthal]

Im actually not using built in reports because I dont need all that data or all those cycles
Im collapsing what I need into a command.report instead, but theres no way to schedule things from bitlash, so I made this and I think it might be handy.

timer.starta(10000,"power.report",1);
timer.stopa

went with letters instead of numbers to not confuse with timer0, timer1 etc on arduino

I actually kind of like this for the events system too. Then if you events.stop you actually get those 3 timers back too.

[jacobrosenthal]

Could also see some timers, or even the events system as module