Adds a prompt token %! which toggles "autocolor mode" on and off.

Example:

%!<&c%h/%H %m/%M %v/%V>

This will show hp, mana, and movement points, and will
color the stats based on how full they are.

"Beautification" starts with the first %!, ends with
the second %!, starts again with the third %!, etc.

Example:

&c<%h/%H %!%m%!/%M %v/%V>

This shows your hp, mana, and movement, but only the
mana is "beautified". The hp and movement are not.

See the preamble at the beggining of the actual snippet for an exhaustive list of what prompt tokens have what autocoloring behavior when autocoloring is enabled with the %! token.