Working toward making the number of markers load dynamically.
Added a simple data.c3d file (from CMU dataset http://mocap.cs.cmu.edu/subjects/02/02_01.c3d ).
Adjusted the map files to the new data.
Updated project to be compatible with Qt5.
Removed mygraphicsscene (it wasn't doing anything anyway).
Fixed (sort of) a bug in the marker widget.

Including a small data.c3d file seems like the thing to do so that
someone can run the project out-of-the-box.  At least that's the goal.
Fixed problems persisting in previous commit

Removed additional constant marker assumptions.
Removed code cruft.
Fixed incompatibility with QuatCamera and Qt 4.x by
completely removing QMatrix4x4.
Added mouse-control to the camera

Left-click and drag to pitch and yaw
Right-click and drag to roll and yaw
Middle-click and drag to translate
Scroll-wheel to move forward/backward
GUI Overhaul

Re-organized interface elements.  Hopefully they make more sense now.
I tried to group and label things.
Got rid of some unused buttons.
Moving toward dynamically loading marker data:
MarkerData group shows how many frames and markers have loaded.
Merge pull request #6 from josephcooper/master

Working toward making the number of markers load dynamically.