implementing a temp monitoring solution
added LP_PS1_POSTFIX
add configuration options and temperature mark
prevent the feature from breaking systems that can't run the "sensors" command
make LP_TITLE works under macos
Fix PKGBUILD
Use print -P instead of echo for printing %~.
propsing a fix for issue #159
Merge https://github.com/f4hy/liquidprompt into develop
Update the doc about the postfix, add an author.
Optimize _lp_proxy
Fix credits
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
fixing a bug in the execution of git rev-list
Optimize _lp_shorten_path by using bash/zsh features

Optimizations:
- move variable declaration in blocks where they will be used
  (so they are not computed in blocks where they are not used)
- "local -i" for integer variables
- if [[ $(( ... )) -gt $(( ... )) ]]   ==>  if (( ... > ... ))
- i=$((i+1))   ==>  let i++
As a side effect the readability of the code is improved.
Optimize _lp_in_multiplexer

Use the return code of the function to return the value instead of
stdout.
Major fix for brackets in terminal multiplexer

Optimize terminal multiplexer detection by moving it to the initial
loading instead of at each prompt display: the terminal multiplexer is
always a parent process and that can not change during the shell life.

This also fixes a major leak: LP_MARK_BRACKET_OPEN was growing at each
prompt display when running in a terminal multiplexer.
(check with: echo "$LP_MARK_BRACKET_OP" | od -c )
bugfix: do not increase the bracket colors when sourcing
Merge branch 'master' of https://github.com/jpec/liquidprompt into develop
Merge branch 'optimize-http_proxy' of https://github.com/dolmen/liquidprompt into develop