Don't automatically set P4PORT (leave this to the user).
Remove unused user settings p4-sendmail-program and p4-user-email.
Put the P4 menu next to "Version Control" in the Tools menu.
Remove function p4-get-p4-port and replace it with p4-info in the menu.
Simplify p4-set-p4-port.
p4-revert shows you the diff for the file you are about to revert.
Fixes #17.