fix: Qt-only version now focuses on files passed via commandline, too

CCBUG: 323673
load multiple files in one instance

A freedesktop.org-compliant file manager would create 20 Marble instances if 20 files were selected for loading in Marble.
The new behavior is to create just one instance where the 20 files are loaded.

REVIEW: 112165
SVN_SILENT made messages (.desktop file)
MarbleRunnerManager.cpp: Fix mingw64 compiler error

Cast to (quintptr) instead of (long) in debug messages.
Fix polyline decoding.

CCBUG: 323772
don't install headers of some unexported classes
work around network dialog popping up under Maemo5 by assigning a dummy QNetworkAccessManager

When the legend widget became visible under Maemo5, a popup dialog appeared asking whether to go online if the device was offline.
Assigning a dummy QNetworkAccessManager prevents the annoying and unneeded popup.