Update library interface with new function to set navigation input shortcuts

[janadamec1]

Changes to (deprecated) library:

1. new exported function to set InputShortcuts to Navigation
2. Fixed crash bug when reopening the scene using library interface (nilling MainScene pointer after close)
3. Better exception reporting - function name added

I've tested the functionality inside my app.

This pull request also fixes compilation of C++ example applications using the library interface (cpp_winapi_library_tester, qt_library_tester). I've also added some Visual Studio folders (used in cpp_winapi_library_tester) to gitignore to have the clean output.

Thanks

[michaliskambi]

Thank you very much! I noticed your work in the branch yesterday. All perfect, no comments, applying :)

In particular thanks for the if Navigation.Camera <> nil then -> if Navigation.Camera = nil then fix in castlescenecore.pas, that was a dumb mistake from my part. It seems I did it during 8145ad2 , and I mistakenly used <> instead of = and never checked whether it works.

Note that we have a a number of automatic tests in CGE in tests subdirectory, if you want to add a test making a AddViewpointFromNavigation call (to make sure that such simple mistake will never again occur in the future), you're welcome!