Many examples unbuildable in binary Qt5 packages

In the binary Qt5 packages, many of the example programs cannot be rebuilt by the user because of missing files. This significantly reduces the value of such example programs to the user.

Background:
In Qt4, the precompiled examples were packaged by taking the source directory after building, just removing the object files.

In Qt5, the packages instead uses the results of "make install". However, many examples do not specify all required files in the install target in the .pro file. In particular:

• Many of the C++ examples do not install the resources (e.g. png files for icons)
• The QML examples do not install the .qmlproject file, so the example cannot easily be opened from creator
• Some of the C++ examples depend on some common code, built as a static library (e.g. demo_lib.lib and pnp_basictools.lib) - those are not installed.