Update libgit2

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Add certificate check dialog for unknown/self-signed certificates

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Merge branch 'libgit2-certcheck'
Reset: Show progress and handled files when used with libgit2

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

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Fixed issue #2323: TortoiseGit does not pull --tags despite checking Tags

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