Workaround for the issue when drag'n'drop to Cura's window does not work on Mac OS X.

[2.9.4](https://github.com/wxWidgets/wxWidgets/blob/WX_2_9_4/src/osx/cocoa/window.mm#L2075-L2091) vs [2.9.5](https://github.com/wxWidgets/wxWidgets/blob/WX_2_9_5/src/osx/cocoa/window.mm#L2203-L2223)

This PR also updates STLQuickLook plugin. Unfortunately is still does not work (not crashes at least) due to [known issue](https://github.com/zaggo/Pleasant3D/issues/13).