Add alarm function

[kolalde]

• piezo alarm (alternating duration). Single frequency
• drive from MPR pin
• non-blocking
• disable with any button touch
• controls via web. On/off, time/day
• set brightness to high on alarm
• RGB flash/bright
• restore to saved RGB/ display level when alarm dismissed

[kolalde]

Added support for piezo alarm (hardware through MPR). Still need to add all software support.