[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
Improve 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.