Add lm75 module for LEGO NXT Temperature sensor support.
more sensor changes

* Lots of documentation - for autogenerating website doc pages
* Added name to sensor info so we don't have to use id_table for
  reverse lookup.
* HiTechnic NXT Sensor Mux data is now read all at once instead of
  in two chunks. Also, extra data is hidden.
* Reverted msensor address attribute to hexidecimal format.
Fix setting legov3_uart msensor mode

* Extended timout to 500msec
* Added retries so that data is resent.
* Fixed false busy indication when writing mode repetedly without delay.

fixes ev3dev/ev3dev#154