[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
Fix lesspipe.sh detection in custom PATH

The detection of lesspipe.sh has to be done after setting PATH as it
could be installed in a non-standard bin directory. For example,
Homebrew installs lesspipe in /usr/local.
[Fix #383] Do not set $MANPATH

man dynamically searches for man pages based on $PATH.
[Fix #385] Do not set $INFOPATH
[Fix #381] Remove the path_helper workaround
Use $GNUPGHOME in GPG agent startup

Use the value of $GNUPGHOME, to facilitate moving GPG's home.

This lets users who keep their GPG keyring on external devices or alternate
folders use the gpg-agent autostarting, even if $HOME/.gnupg does not exist.
Add support for nvm
[Fix #351] Set empty keys to an invalid UTF-8 sequence
Merge branch 'master' of github.com:sorin-ionescu/prezto