Merged /tags/beta14@38 /branches/release/beta15@43.
Use 'haslocaldir()' if available to correctly handle windows that used :lcd.
Made VCSDiff pass-through.
Fixed SVK VCSDiff implementation.
Made VCSCommands work a bit better on directory buffers (netrw).
Replaced delayed extension registration to directly loading the main plugin from
extension plugins. This allows base functions declared in the main plugin to
be used in the extensions.
Fixed SVN diff to actually use 'VCSCommandSVNDiffOpt' option.
git-svn-id: https://vcscommand.googlecode.com/svn/trunk@44 e7462f97-9721-0410-a4e7-d7c98e439057