[vile] system-mapped-chars

[Wayne Cuddy]

Can system-defined maps be adjusted after compile time? It doesn't
seem so.

I've found that HOME/END keypad keys don't always map to #H/#E
respectively.

I've been able to get around this with additional maps for
terminal-specific sequences in the vilerc file but it would be nice if
there was an easy way to add to the system maps.

Wayne