Update libgit2

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Fixed issue #2385: 'Mail' - 'Use configured server' & 'none'... seems can not be localized

Signed-off-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>
Update warning for old Git for Windows versions

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Update Git for Windows website

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Better distribute version checks over all week days

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Fixed issue #2356: Rebase dialog should also auto-link to issue tracker

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Refactored: Move CheckHeadDetach() into CAppUtils

Signed-off-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>
Warn user HEAD detached after rebase done

When choosing a non-local branch, such as FETCH_HEAD, as Branch,
the HEAD is still detached after rebase done.

Therefor, it's needed to warn user and provide a way to create new branch,
so that the changes might be not lost for further operation, such as checkout.

Signed-off-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>
Use original branch name of rebase as default name of creating new branch

Signed-off-by: Yue Lin Ho <b8732003@student.nsysu.edu.tw>