TortoiseGitMerge: Fixed possible crash while applying a patch

Signed-off-by: Sven Strickroth <email@cs-ware.de>
TortoiseGitMerge: Use shipped zlib1.dll instead of own copy

Signed-off-by: Sven Strickroth <email@cs-ware.de>
TortoiseGitMerge: Updated libsvn stuff

Signed-off-by: Sven Strickroth <email@cs-ware.de>