Update libgit2

Mainly to fix CRLF issues of git_blob_filtered_content (https://github.com/libgit2/libgit2/issues/2393).

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Fix possible resource leaks

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Fix C&P error

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Do not initialize member variable twice

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

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Rebase Dialog: Can move commits to top/bottom of list if Shift key is pressed when clicking up/down button

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>