Add the most recent rgb.txt from upstream as part of the package,
installed to ~/.vim. Accordingly, CSApprox.vim will now search in all
dirs in &rtp, in order, before deciding that no rgb.txt could be found.
- Update "Last Changed", version number, and changelog
- Suggest installing larger vim packages as a workaround for no +gui
- Modify the way g:CSApprox_verbose_level works; now 'verbose' is set to
the max of that variable and &verbose
- Fix a minor bug causing a complaint that not enough colors are
available when changing colorschemes after a :gui
- Fix some comments
