implemented 2 rendering variations

- fixed bug: bended rendering (now everything looks like it should)
- fixed bug: camera position and ray orientation
- fixed camera bug (now the camera is drawn with the correct ratio; 4:3)

- adjusted and optimized fShot and fCalc (much faster now)
- activated second implementation of intersection algorithm (matrix
    multiplication)
- changed size of image viewer window
- changed standard values of cameras
- added variable to change render mode (cGlobal::gRenderMode) not in
    Debug Interface yet (I'm soooo tired)
- adjusted image viewer window (has the correct size now)