This stops any active music playback, which is handy if you did a warm
boot in the middle of playback, and your The Cricket! is stuck playing
the same note constantly but you don't want to power-cycle the device
which will unset the RTC.
c/o @frankmilliron
... and don't bother saving/restoring registers during install,
as this will only follow a boot or OS restart.
Suggested by @frankmilliron
Also inhibit interrupts in the SET.XXX utilities for good measure.
This one driver pulls in the installers for each other clock driver,
and invokes each in turn:
* No-Slot Clock
* ROMX
* FujiNet
* DClock
* Cricket!
This requires adding `.ifndef JUMBO` guards in the other drivers for
when they pull in include files (symbols, macros, etc). The other
drivers are adjusted to return with carry clear on successful install,
failure otherwise.
