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- upgraded min/max/robust-stat calcs to better ignore NaN/Inf in displayed images & stats-box/photometry calculations
- changed colors of curview_rectangle in OverviewImagePanel and zoom_rect in PrimaryImagePanel to match and be orange, which in tests looks better than the old dark green (overview) and magenta (primary) and makes more sense to have be matching
- reduced initial delay in CommandListenerThread to 10 seconds (had been 1 minute) to reduce potential confusion about zombie ztv windows
- fixed a matplotlib warning bug annoyance - problem was __about__.py imports one routine from astropy_helpers, but astropy_helpers has some (unrelated/unnecessary for our purposes) matplotlib code. Fix was to include the astropy_helpers.git_helpers code directly within ztv, to avoid both the annoyance warnings, but also blocking pylab.show() from working correctly at times in the underlying python session.
- re-factored phot_panel, plot_panel, stats_panel almost entirely out of ztv.py main module for clarity/maintainability reasons. (ztv main module still has few hooks into stats_panel regarding doing auto clim setting from stats box, but that seems acceptable at this stage)
- fixed recently introduced bug that was causing accelerator key strokes to fail in primary_image_panel
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