Doc: added excludedirs to qdocconf example.

Corrected style issues pointed out in review.

Task-number: QTBUG-31801

Change-Id: Ibbc4e5f8dcd8ca129ae945b5e62b15daed47d86d
Reviewed-by: Martin Smith <martin.smith@digia.com>
Windows: Keep monitors when system is locked.

Prevent windows from being recreated due to screen changes which
can cause GL widgets to stop updating among other things.

EnumMonitors returns only one temporary monitor named "WinDisc"
when locked. Do not remove monitors when that happens.

Task-number: QTBUG-33062
Change-Id: Ia2247bb04b3e10f99f594245f84238b5f9044f70
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Return 1.0 for devicePixelRatio in QCocoaWindow if no valid window

If m_window is invalid, devicePixelRatio returns 0, which leads to
adverse effects in other parts of the code. For example,
qquickshadereffectsource.cpp will get stuck in an infinite loop
trying to multiply 0 by 2.

Task-number: QTBUG-32975

Change-Id: Ie3db86f1f459df018ebce67bcb4226f6cffe854e
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>