contrib/git-svn: stabilize memory usage for big fetches

contrib/git-svn: stabilize memory usage for big fetches

We should be safely able to import histories with thousands
of revisions without hogging up lots of memory.

With this, we lose the ability to autocorrect mistakes when
people specify revisions in reverse, but it's probably no longer
a problem since we only have one method of log parsing nowadays.

I've added an extra check to ensure that revision numbers do
increment.

Also, increment the version number to 0.11.0.  I really should
just call it 1.0 soon...

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>