pause/restart functionality added to the scheduler

Hi,

Please ignore the formatting diffs, they originate from code editor's autoformatter.

The real change I made was to add two functions.
pauseScheduler(): puts the scheduler on hold by disabling WDT interrupts
restartScheduler(): re-enables WDT interrupts so that scheduling can continue as normal

Why? I thought that it would be nice to prevent WDT ISR from waking up the system from sleep. And after waking up from a sleep period, what would be nicer than to re-enable WDT interrupts to have scheduling running again.

Great work with leOS2, by the way!