Fix misaligned selection region with text when centered

If the text is centered, the x/y position in the selection QRectF may
be a multiple of 0.5 which is rounded up. This rounding causes
misalignment of the selection region with the text.

The alignment is fixed by using qFloor on the x and y components.

Task-number: QTBUG-34218
Task-number: QTBUG-34234
Change-Id: I4f2fadeb38602f62a93773c6e5faecf03b28069f
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>
(cherry picked from qtbase/5d8a882c11201a29475c5ea71cfb76c9de6573f5)
Fix compilation of Qt Script with MSVC 2013.

Starting with MSVC 2013, more functions are provided.

Change-Id: Iabbc9a94e7ed01584baaa1bb17c06e41ac70830f
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
(cherry picked from qtscript/24d678ce9c3996f46d1069c2b1193e7ec1083fc8)
Introduce Windows version 8.1 and detect by checking the version.

Change-Id: I04012218c34f7a95a87fcf2dc7fc095f0e743e67
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Reviewed-by: Björn Breitmeyer <bjoern.breitmeyer@kdab.com>
(cherry picked from qtbase/dff6d73d6c37c40790d90bfdf3cb2f6e75c5bfa4)