Cleanup gcoder.py indent
Remove orphaned code
Start cleaning up gcode measurement code
Fix and cleanup used filament length measurement
Move code around and remove useless helpers from pronsole.py
Woops, fix a typo
Missing import
More cleanup on gcode measurement
Woops, typoz
Speed up various parts of gcoder GCode processing
Cleanup some code in pronterface
Cleanup duration estimation

Estimation duration now uses the already parsed GCode instead of reparsing it.
It also computes a per layer duration estimation which can probably be used to
produce better ETAs.

The only difference is that it does not compute duration for Z layers changes,                                                                                                                        but it was probably super wrong already given how it is done (it only changes
the estimation by than 2s over 2 hours of print and 54 layers, and the feedrate
stuff mixes all the axes together).

I also detected a few potential issues in the code, which are marked by FIXMEs.
Use GCoder parsed gcode in gviz
Minor cleanups in pronsole.py

Command line option parsing really needs a better rework, to use optparse or
argparse and support gcode/stl filename argument.
Remove debug statement in gcoder.py
Minor presentation error fix in pronsole.py
Replace getopt CLI option parsing with a cleaner argparse parsing
Add argparse dependency to README.md
Speedup full file gcode loading in printrun/gviz.py

FWIW, on my test system with my test GCode loading time goes down from 5.7s to
2.3s between b3a673bc97 and this commit, that's almost 60% gone.
However, there is still a lot of room for functional improvements :
- I don't think the roundtrip through the target array is useful
- There's no handling of relative coordinates (neither for position nor for e)
- The arcs drawing code might be wrong
- The stlview bits are not enabled and probably have to be looked at and updated
Move gcoder.py into printrun module