Add QML bindings for CloudSync API
[API change] remove unused class GeoImageGraphicsItem

This is a follow-up on commit 94e7af1b18279651283700361b139474eb746b16, which implemented ground overlay rendering based on TextureLayer.
Since GeoImageGraphicsItem didn't implement the spherical case and isn't considered by the GeometryLayer any more, it should be removed.
mark method of private class as static
reuse QStringList rather than QStandardItemModel object
mark getters as const and remove from slots section
remove Maemo5 reminders
Qt bug reports are now on qt-project.org
don't leak mapTheme

When !mapTheme->head()->visible() was true (e.g. for the srtm2 theme), the GeoSceneDocument object was leaked.
Replace deprecated qVariantValue<T>(x) with x.value<T>()
Replace the last qVariantValue
Qt5 preparations: toAscii becomes toLatin1
QImage::numBytes is obsolete, use byteCount instead.

Also rename internal StackedTile method to reflect that.
Less code and a bit prettier
Provide input fields to change credentials. Tweak size and space.

Note: changes to credentials are not properly propagated yet.
Give a hint if monav-routing-daemon is not installed on the system.
remove unused private slot
[API change] split MarbleRunnerManager (separation of concerns)
const'ify
add timeout as a parameter rather than hardcoding it
[API change] remove enum for unimplemented MGRS angle notation