Simplify the "lite" package even more

Make the only differences between "lite" and "regular" vim just console
mode and no language bindings. This was already the case (the default
feature set is "huge"), but now it's explicit.

Add a pkg-descr to vim-lite that explains the above, and remove some
text in the pkg-descr that makes absolutely no sense.

There's no effective change to generated package, but the port is
getting updated tomorrow anyway.

This will facilitate the future removal at some point of the "lite"
package, so that it can be replaced by a "console" flavour.

While here, remove a variable that was last used in 2001.