implementing a temp monitoring solution
add configuration options and temperature mark
prevent the feature from breaking systems that can't run the "sensors" command
add commentaries and a selection process for temperature source

* add a function selection process at loading time so liquidprompt can use other command than sensors to get temperature
* add commentaries
Merge branch 'feature/temp' of https://github.com/jaesivsm/liquidprompt into jaesivsm-feature/temp

Add the temperature threshold in the RC file

Conflicts:
	liquidpromptrc-dist
More the temperature mark before the colored value

Because the θ character may be confused with a 0, which was less readable.
Move the temperature before the jobs, with other sensors
Update the README with the temperature feature