Upgrade libgit to 1.8.5.2

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Disable close button by default

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Enable Abort button in thread in order to prevent unintentional aborting

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Fixed issue #1860: Race condition in git.exe Progress Dialog

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Merge branch 'issue-1860'
Display warning if thread could not be started

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

This was only used in "Submodule update" command and did not work since 2011.

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Flag constants as const

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

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Rename dialog handler name

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Trim quotes from cli parameter

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Merge branch 'sshaskpass'