This is a merge+manual adaptations of numerous commits on Qt4

(cherry picked from commit 99b7cf3c)
(cherry picked from commit 7e26f748)
(cherry picked from commit 8abd25d4)
(cherry picked from commit a736053c)
(cherry picked from commit 312d9c3f)
(cherry picked from commit 6fac9321)
(cherry picked from commit df261c30)
(cherry picked from commit a7009554)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>