add some remote actions and reenable sleep
Support code for Si570 oscillator
Fix RFREQ frac part calculation
Improve the tests for si570
Update most of the code to use new frequency type
Update code to use the Si570 chip and new code for frequency display
Add forgotten file
Change freq representation and make I2C and Si570 routines be interrupt based
- frequency has it's own type (32b fixed point, 1 fractional bit)
- display frequency changes delayed until confirmed by Si570 callbacks
- introduce error reporting to display (red button resets errors)
Use crystal and a bit sparter logic for si570