Let GravatarThread access the exit flag pointer instead of member variable after instance destroyed

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Fixed issue #2159: URL combo box in Submodule Add is not case sensitive

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Revert "Fix resource leak: Close the event handle in the destructor"

This reverts commit e11eba99fd171471288026b022621f160b561cd0.

(fixes issue #2160)

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