[Vimprobable-users] RFC: Added support for buffers

[Morgan H. <mt...@gm...>]

This patch adds basic support for handling multiple buffers. New
commands are ":buf[fer], :badd, and :bdelete". Buffers are given a
unique constant buffer id starting at 1 in the same manner as vim.

The :badd command takes an optional url argument which it will open
when creating the buffer. If none is provided, it will open a new,
blank buffer.

The :buf[fer] command allows changing to another buffer in the buffer
list and supports tab completion.

The :bdelete command also supports tab completion and takes an
optional buffer argument and deletes it. If no argument is provided,
the current buffer is deleted.

I tried to as closely as possible follow the behavior in vim so that
it would be familiar to use and have been using it for several months
now. The buffer naming used in the tab completion is kind of clunky
but it works well enough. Other than that, I haven't had any serious
problems or complaints.

Please discuss if this is even something we think is worth adding, if
we should make it a compile time conditional feature, if you have
better suggestions for the implementation or tab completion, etc. I'd
appreciate any feedback. And of course please try it out. :)

*NOTE: This patch builds upon my previous patch just submitted to the
list regarding the commands list and COMMANDSIZE variable. These 2
patches are obviously conflicting, so you'll need to apply that one
first to test the buffer support. These changes are also in my
for-next branch on SF.

Regards,
Morgan