GNU Screen and Vim: making vim tab mappings work

if using Vim in GNU Screen and you want to use fancy key bindings to navigate tabs, first make sure the below is set in your .vimrc file

set term=xterm

this will allow Ctrl+PageUp/Down to work to switch tabs

if you want to use Alt+Up/Down add the below in

map <M-up> :tabprevious<CR> 
map <M-down> :tabnext<CR>