Raytraverse

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* organized command line code
* use process pool for sun sampler when raytracing is fast (such as -ab 0 runs with dcomp)
* propogate plotp to child sampler if sampling one level
* separated utility command line to own entry point. fixed ambiguity in
coordinate handedness of some functions (changed kwarg defaults)

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* fixed rcontrib to work with Radiance/HEAD, radiance version string includes commit
* daylightplane - add indirect to -ab 0 sun run (daysim/5-phase style)
* lightpointkd - handle adding points with same sample rays
* sampler - add repeat function to follow an existing sampling scheme
* lightresult - added print function
* scene - remove logging from scene class
* cli.py
* new command imgmetric, extract rays from image and use same metricfuncs
* mew command pull, filter and output 2d data frames from lightresult
* add printdata option to suns, to see candidates or border
* make TStqdm progress bar class public
* include PositionIndex calculation in BaseMetricSet
* new metrics: loggcr and position weighted luminance/gcr
* skymapper: filter candidates by positive dirnorm when initialized with epw/wea
* imagetools: parallel process image metrics, also normalize peak with some
assumptions
* lightresult: accept slices for findices argument
* sunsamplerpt: at second and thrid sampling levels supplement sampling with
spec_guide at 1/100 the threshold. helps with imterior spaces to find smaller
patches of sun
* positionindex: fix bug transcribed from evalglare with the positionindex below horizon

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* command line interface development

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* improved documentation

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* refactor code to operate on a single point at a time

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* create and manage log file (attribute of Scene) for run directories
* possible fix for bug in interpolate_kd resulting in index range errors
* protect imports in cli.py so documentation can be built without installing