convert all non-verbose Serial.print to sp, reformatting as necessary
update the float printer and make avail, use in a volts command
Merge pull request #174 from Pinoccio/serialprintless

never Serial.print (except verbose), print floats, pin.status json and power.volts
Merge branch 'master' of https://github.com/Pinoccio/library-pinoccio into meshcalibrate