Configurable channels. Minor fixes to ADC CLI (current monitoring setup)...

..., enhancements to RSSI CLI in RX CLI, some other minor stuff

Allows up to 12 channels on serial and spektrum, only 8 on parallel. CLI prints them accordingly, processFlightCommands reads them accordingly. I think this is a pretty good way of doing it, I tried to minimize if statements to keep it fast.
drv_rx.c might need to have that "12" in the init function changed to eepromConfig.serialChannels, not sure it really matters.

OSD defaults changed to PAL
RSSI CLI updated so it switches the settings to either PPM defaults or ADC defaults such that you don't have to enter anything else.

I've tested this with 9 channels turned on, haven't tried any more. Parallel PWM should still work but you should test it, I can't test Spektrum.

Chip