vim: firefox-like tab controls

I approve of this tip to make tab navigation in vim the same as with firefox. Life is too short to memorize multiple sets of commands.

:nmap  :tabprevious
:nmap  :tabnext
:map  :tabprevious
:map  :tabnext
:imap  :tabpreviousi
:imap  :tabnexti
:nmap  :tabnew
:imap  :tabnew