Cmake build: Use find_package(Qt5X11Extras ...) independent of OS

We need to know, if Qt5 is built over X11 in order to test with
xvkbd, which manipulates XEvents.
Qt5X11Extras is independent of underlying OS.
Correct the method signature of MenuTranslator::translate for Qt5
FSPathMakeRef is deprecated: use LSOpenFromURLSpec instead of LSOpenFromRefSpec
Remove special GlobalMenuBar class. As Patrick De Visschere pointed out it is not needed. The shortcut handling of Qt does it internally now what GlobalMenuBar was made for.
Remove superfluous class definitions.
Reintroduce some class definitions.
Qt5MacExtras is required on a Mac; report the version of Qt5
support for the LaTeX commands \x***arrow

- this patch supports the \x***arrow commands provided by the mathtool package
- fileformat change
FORMAT: document latest file format change
Fix stalling of keytests when invalid DISPLAY

Before, the keytests would run infinitely if the
tests were run, e.g. through SSH without X forwarding.
To reproduce that problem, run

  DISPLAY='' ctest -R hello

This commit causes the test to correctly fail in such situations.
(Collaboration with Scott Kostyshak)
keytests: add a timeout for LyX process to start

If the LyX window does not appear after a certain (conservative)
time, the keytest now fails. One reason that caused the LyX window
to never show up was when DISPLAY was not set. This particular case
has been fixed in <commit1hash>. This commit is meant for the more general
scenario.
(Collaboration with Scott Kostyshak)
* sk.po
keytest.py: Allow for LyX window to appear without timeout

Timeout for lyx-process to appear may be significantly smaler.
5 sec. looks sufficient, while lyx-window may take some time
due to configure.py.
Add a debugging message.
Fix the -geometry command line argument for Windows.

The command line argument -geometry WIDTHxHEIGHT±XOFF±YOFF
specifies a preferred size and location for the main window.
Currently, this is semi-broken on Windows. Indeed, only
specifying WIDTH and HEIGHT places the main window such that
the left and top borders are invisible such that the window cannot
be moved. Moreover, the XOFF and YOFF parts (when present) are
used to specify the distance of the window from the left and top
or right and bottom edges of the screen, when using '+' or '-',
respectively. However, -geometry 800x600-20-20, instead of placing
the window such that its bottom and right edges are at a distance
of 20 pixels from the corresponding screen edges, places the
window such that its left and top borders are out of the screen.
This is corrected by this commit, which also addresses the fact
that Qt5 does not define Q_WS_WIN anymore.
Replace Q_WS_WIN with appropriate guards to account for Qt5.

This commit replaces almost all occurrences of Q_WS_WIN to comply
with Qt5. The remaining occurrences should *not* be replaced,
because the guarded code won't compile on Qt5.
#9245 replace Q_WS_MACX with Q_OS_MAC - the Q_OS_MAC macro is usable with Qt4 and Qt5.
Correct LyXUtilitiesDir default assignment location (thanks Patrick)
More careful NSAutoreleasePool management
print callstack on assert