Merge branch 'qtupdate' into master

It appeared that Eelco DOSTRA already made an update for it.
Unfortunately, his update was not complete as the dlopen-gtkstyle patch
didn't worked anymore.
This ommission can be explained by the fact there is (apparently) no usage
of the gtkstyle qt option in nixpkgs.
Also, and because Nokia abandonned Qt, I changed the homepage to match the
new url of Qt's open side (qt.digia.com is only for the commercial one).

Signed-off-by: Baptist BENOIST <return_0@live.com>