- feature : add DX11-specific implementation details.
- feature : add class SystemDialogSelector to support openfile-dialog.
- feature : add opendialog option to the model viewer.
- update  : add missing documentation.
- bugfix  : support lower- and upper-case key events.
- bugfix  : fix a crash in trackball, when no node is attached.

Signed-off-by: Kim <Kulling>
bugfix : add missing file.

Signed-off-by: Kim <Kulling>