Deduplicate code

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

Signed-off-by: Sven Strickroth <email@cs-ware.de>
TortoiseShell: Enable drop patch handler

Signed-off-by: Sven Strickroth <email@cs-ware.de>
TortoiseShell: Make  DropCopyAdd handler work

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

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