Gnu Screen Vertical Split patch

The patch from the original author doesn't apply cleanly and so I
had to edit the source files manually to add the code from the diff:
http://vsp4sdl.yuggoth.org/wrp_vertical_split_0.3_4.0.2.diff.bz2.

Homepage for the vertical split code: http://fungi.yuggoth.org/vsp4s/.