Console: readLine method improvements.

* CTRL+Z is a return-carrier like CR and LF. Not the greatest idea but we could change it later to make it more generic.
* If no OutputStream is specified, the the method doesn't produce any echo.
GPS: Documentation + NMEA parsing improvements.
Basic HTTP control: Added some documentation.
Adding some internal sensors monitoring tasks.
GPS: Improved some parsing code.
Watchdog: Embedde watchdog is setup to restart the first time the program loads.
Merge branch 'master' of github.com:fclairamb/tc65lib