- Add an optional argument to flightgear::initApp(): doInitQSettings.
This argument defaults to true, preserving initApp()'s behavior in
this respect. If this argument is set to false, FGGlobals doesn't have
to be initialized.
- New function flightgear::initQSettings(), called by
flightgear::initApp() when its 'doInitQSettings' argument is true.
This allows initializing the QSettings exactly when it is needed.
- New function flightgear::checkKeyboardModifiersForSettingFGRoot().
The code it contains used to be run from initApp(), which is
undesirable because:
1) initApp() is not only called at FG initialization (fgMainInit()),
but also from QtMessageBox(), from QtFileDialog::exec() and twice
from Options::setupRoot(). However, checking the Alt and Shift
modifiers to set 'fg-root' in QSettings to the special value
"!ask" only makes sense in fgMainInit(), not in these other
places.
2) This code relies on the QSettings to be set up, and therefore on
FGGlobals. Thus, freeing initApp() of its dependency on FGGlobals
requires splitting this keyboard modifiers checking code out of
initApp().
