Fix build-ability of installed examples

Summary:
* creates fake headers in marble/ prefix in the build dir for headers
  which are not in lib/marble in the sources, to simulate install paths
* update all installed CMakeLists.txt to cmake config file logic
* fix missing installed sources or CMakeLists.txt
* temporarily stop installing sources of marble-game,
  needs some work for paths of flags in qrc file

OPENCV-based examples were not touched, need a separate look

Test Plan: All installed example sources could be build with cmake & make, and ran.

Reviewers: #marble, rahn, sanjibanb, shentey, nienhueser

Differential Revision: https://phabricator.kde.org/D2373

# Conflicts:
#	examples/cpp/marble-game/GameMainWindow.cpp