Don't drop comments in gcoder, we might use them in printcore

Modify regexps and remove ; filtering
Initial untested implementation of gcoder-based printing.
Move GCodeAnalyzer.py to printrun/
Workaround for OS X: drop -psn* arguments before parsing args

OS X adds this "process serial number" argument automatically when launching an
App or similar situations. We don't care about this argument and drop it before
parsing the args using argparse.
Handle OSX MacOpenFile and MacOpenURL events
Start merging gcoder and GCodeAnalyzer by reusing gcoder parsing
Run reindent on GCodeAnalyzer
Start updating stlview to use gcoder parsed GCode
Don't disable shadow window in stlview as it leads to a bad mess
Refactor gcoder a little to precompute positions and extrusion status
Import actors.py and vector.py from libtatlin
Drop StlModel from imported libtatlin.actors
Rework libtatlin.actors to use pyglet and fit into our framework

Several small modifications were required, such as providing build dimensions,
adding some flags, translating numpy arrays into pyglet VBOs and using the
right pyglet GL API function names.
Rework gcview to make it cleaner, better and faster
Update printrui/gui.py with respect to gcview changes

This commit introduces a use3dview flag, which will be made as an option as
soon as we get a better options GUI.
Minor cleanup
Display already printed lines in a different color in gcview
Disable arrows in gcview
Cleanup
Add forced coordinates parsing and S coordinate parsing