New macro: ACTION_BACKLIGHT_LEVEL(level)

To have full control of the backlight level.
Merge pull request #110 from xauser/master

Enhanced Backlight Support
Change PollingIntervalMS to 10ms(Fix #114)
Return when ready check loop is timeouted(Fix #115)
Change LUFA build options
Fix 'Shift Parentheses' example
Move macro definitions from lufa.c to lufa.h
Add LUFA git repository(release 140302)
Fix description of pin usage
Change MCU setting to ATmega32U2
Merge remote-tracking branch 'upstream/master'