git-svn: added an --include-path flag

The SVN::Fetcher module is now able to filter for inclusion as well
as exclusion (as used by --ignore-path). Also added tests, documentation
changes and git completion script.

If you have an SVN repository with many top level directories and you
only want a git-svn clone of some of them then using --ignore-path is
difficult as it requires a very long regexp. In this case it's much
easier to filter for inclusion.

[ew: remove trailing whitespace]

Signed-off-by: Paul Walmsley <pjwhams@gmail.com>
Signed-off-by: Eric Wong <normalperson@yhbt.net>

contrib/completion/git-completion.bash

@@ -2451,7 +2451,7 @@ _git_svn ()
 			--no-metadata --use-svm-props --use-svnsync-props
 			--log-window-size= --no-checkout --quiet
 			--repack-flags --use-log-author --localtime
-			--ignore-paths= $remote_opts
+			--ignore-paths= --include-paths= $remote_opts
 			"
 		local init_opts="
 			--template= --shared= --trunk= --tags=