Revert "Remove temperature gauges entirely from codebase"

This reverts commit 02ef52d777847d24e4f99de847686d8927ad6629.
First step towards getting the gauges optionally back for #296.
Fix possible issue where checksum would break layer change detection

Should fix #348
More work on getting the gauges back
Add -g/--gauges CLI argument for temp gauges, and improved argparsing.

The gauges options is a CLI parameter as having it as an option would be
too painful to handle for now.
Argument parsing has been improved so that pronterface can add its own CLI
parameters in addition to pronsole's ones.
Correctly draw right edge shadow for temp gauges
Expand gauges as much as possible
Cleanup some code

Not sure about that dropping of the self.gwindow.Destroy try block, we'll see
Fix #363 by correctly doing the wxFrame/wxPanel parenting

As far as I understand, a wxFrame needs a wxPanel child, but we shouldn't
reparent this wxPanel to some other container. As a consequence, I created an
initial wxPanel for the gwindow wxFrame and assigned it the previous sizer
(instead of using the gviz panel as the wxFrame's panel).
Not sure why it wasn't segfaulting on my other systems, though.
Merge branch 'experimental' into HEAD

Conflicts:
	printrun/gviz.py