[Fix #355] Do not set launchd environment variables

Setting environment variables for launchd processes is unreliable.
Finder and all Finder launched programs have to be restarted for the
new environment variables to take effect.
[Fix #357] Set alias gcO to check out hunks interactively
[Fix #360] Set alias giR to reset the index interactively
[Fix #349] Display diff when committing
Export $MANPATH and $INFOPATH
[Fix #366] Distinct position with red
Merge branch 'master' of git://github.com/sorin-ionescu/prezto