implemented the @pause gcode host command (and a small framework for host commands)

Pause code (Ported from RepetierHost, untested)

Fix crash on SUSE when setting temperature due to setting temp field background color to "".

This replaces "" strings that cause aborts in python-wxWidgets wxColour_helper with
Python None objects. This corrects an abort where the helper tries to fetch the
first byte of the colour string even when it's 0 length.

Update webinterface.py

oops! :'( web/css/style.css

attempting fix for issue 305

need to explore CherryPy & websockets, but this quick'n'dirty is a big
speed increase

Encountered https://github.com/kliment/Printrun/issues/305#issuecomment-12306186
This edit removed the error, but I don't know what the original output was so I'm not sure if this really _fixes_ it, or is just a band-aid.

Imported and translated from RepetierHost

First commit unfinished implementation

experimental branch: fixing broken pyreadline download url

fixing broken pyreadline download url

[printcore] Have print_thread rejoin execution thread.

[printcore] Switched to use Python if syntax and not Ruby's.

Add checking to pause/resume functions in printcore.py

Confirmation on exit

Make sure to set target temps to 0 before exiting.

To ensure safety, we make sure we set target temps to 0 before we exit
pronsole.

Presently, one might accidentally terminate a print with a CTR-D while
printing. Now we ask the user to confirm exiting if there is a print
going when they try to exit.

Protect the user from typos in setting the extruder temp by confirming
them with the user if they exceed 250.

Conflicts:
	gcoder.py

Support M82/M83 for relative E

Show connection error to the user