Fix compiler warning
Fix touch sense wakeups.

Commit 411307ab fixed a parenthesis warning.  Prior to that,
the test always returned false, and the "corrected" logic doesn't
actually work right.  Instead of waiting on EOSF (which won't get
set if a scan was never triggered), wait for SCNIP to clear, as
is done in Teensy's touch.c.
Use atomic block in DeepSleep/Hibernate, like SleepHandler does
Use yield() in case the user has redefined it to actually do something
Make up a GPIO_WAKE value for this software interface to use and
check.

It won't be passed to the hardware; just used in the config->modules
to indicate that the GPIO pin defintions should be used.  This commit
also replaces repeated constants with LLWU_ definitions.
Only set GPIO pins for wakeup if GPIO_WAKE is set.

Otherwise, any values in config->gpio_pin would still have been used
as wakeup sources.
Consolidate sleep and hibernate logic into a single function
Now that setup is consolidated, no need for extra helpers.
Remove unused comments
Merge branch 'Bleeding-Edge' of https://github.com/duff2013/LowPower_Teensy3 into pr/5
Merge branch 'pr/6' into Bleeding-Edge