Review *all* shell commands after switching to new string library

[oscgonfer]

After recent firmware changes to move to a new library, the parsing of commands on the control interface has gone all awol.

We need to review all the commands listed in the docs.

Here a compilation:

CO2

SCK > control scd30 calfactor
SCD30 CO2: calfactor
Forced Recalibration Factor: 632
SCK > control scd30 autocal  
SCD30 CO2: autocal
Auto Self Calibration: off
SCK > read co2                
SCD30 CO2: 742 ppm
SCK > control scd30 autocal on
GPS Longitude: autocal on
Unrecognized sensor, or no control interface available for this sensor
SCK > control co2 autocal on  
GPS Longitude: autocal on
Unrecognized sensor, or no control interface available for this sensor
SCK > control scd30 co2 autocal on
SCD30 CO2: autocal on
Auto Self Calibration: on
SCK > read co2
SCD30 CO2: 742 ppm

Water

https://github.com/fablabbcn/smartcitizen-kit-2x/issues/60