FWIW, on my test system with my test GCode loading time goes down from 5.7s to
2.3s between b3a673bc 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

Command line option parsing really needs a better rework, to use optparse or
argparse and support gcode/stl filename argument.

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.

fix typo in do_pause() log output

Merging awesomeness

Getting the print queue api working with the printer, adding a job progress panel to inspector and adding job_finished and job_started events.

Throttling the DOM writes of pronserve inspector and stopping dom writes entirely when the window looses focus.

Adding a sleep to the pronserve startup. Seems to be fixing an intermittent bug where the printer wouldn't respond to temperature requests

Refactoring Pronsole to wrap print in a self.log method so that it can be reused and overriden by a web interface or any other non-conosole interface