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- Made default datadir and auto-load pattern be the current working directory (rather than just user's home dir)
- dev2: made temporary fix to ztv.set_clim to force image redisplay even when cim unchanged. Problem was that new images weren't being displayed automatically for a fixed clim. (Need to come back and re-evaluate how images are loaded and look for remaining inefficiencies, e.g. code called more than once during a single image load)
- dev3: speed improvements in areas that will help speed of auto-loading new images; primarily reducing number of extraneous recalculations of aperture photometry
- dev4: speed improvements in areas that will help speed of auto-loading new images; primarily reducing number of times that redraw_*_image routines are called
- dev5: reduce number of times that image normalization is recalculated by caching; modified some syntaxes for easier future upkeep.
- dev6: moved rebinning of overview image (really sub-sampling, not rebinning) from allowing matplotlib to do implicitly to doing explicitly before passing to matplotlib. This speeds things up a lot (0.3sec on a ~2014 MacBook Pro Retina) for large (2K) images.
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