Additional alarms & improved piezo control

The "beeps" alarm has been renamed to "beeps hi" and there is now a
"beeps lo" which provides a lower frequency, and less annoying,
beeps-style alarm.

The new alarms called "pulse hi" and "pulse lo" provide another
traditional alarm style, the three beep pulse, with both low and high
frequency beep pulses.

For birthdays and congratulatory occasions there is a new musical
alarm:  "For He's a Jolly Good Fellow".

A minor progressive alarm bugfix allows for smoother transitions from
low to high volume.

The alarm indicator (0th-digit "-") now blinks while the alarm is
sounding and while snoozing.

Code, comment, and documentation edits make things more clear.