smart_vopen: allow >2 files to be opened in vsplit
smart_vopen: allow >2 files to be opened in vsplit

The previous smart_vopen code was not smart enough to figure out when a
screen was wide enough to vsplit more than 2 files. Although the feature
probably only makes sense for 2-4 files, an arbitrary number of files
are now allowed.

I still haven't touched horizontal splits because I don't like them as
much.

skrulcik/Resources,skrulcik/Resources,skrulcik/Resources,skrulcik/Resources