Implemented first version of ppms interface.
Added beep command.
Added a few more commands.
Fixed PPMS constructor.
Fixed small bug.
Fixed bug in PPMS.beep method.
Merge branch 'develop' into feature-ppms
Merge branch 'develop' into feature-ppms
Implemented status codes.
Added missing brackets.
Added missing type.
Parsing unix timestamp in system status code.
implemented a few more ppms commands.
Added Measurement helper class.
implemented higher level commands, such as set_temperature, scan_temperature and set_field to the ppms driver.
Fixed few erros in Measurement helper class.
Added a ppms example.
Fixed small bug in Measurement Helper and example code.
Changed ppms example code to make it more realistic.
Fixed non functioning simulation mode in write-only commands.