#3 git-svn support

[Dirk Wallenstein]

I played around with git-svn support a bit, but don't have much time to test
currently (Also, I'm wondering if conversion can be generalized
(fast-export?)). For git-svn only, the first patch adds support to x-jhbuild.
To use it add the following configuration before checking out subversion
repositories.

[buildconfig]
svn-program = git-svn

There is a hardcoded branch selection in JHBuild that seems to be unused. Use
the first JHBuild patch to remove that. (spool will not generate an error,
then)

Use the second JHBuild patch to obtain full histories. Otherwise JHBuild will
truncate to the latest revision.

[Dirk Wallenstein]

x-jhbuild: add support for git-svn

[Dirk Wallenstein]

jhbuild: git-svn: remove hardcoded branch selection

[Dirk Wallenstein]

jhbuild: git-svn: do not truncate history