Laserbeamsize

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* Add another figure to readme
* Improve `visual_report()`
* Add `plot_beam_fit()`

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* Add routines to plot values along semi axes
* Add `visual_report()` for simple beam analysis
* Fix error when calculating circular radius
* Add missing scipy requirement
* Improve README.rst with figure

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* Works dramatically better across a wide range of images
* Minor API changes to `beam_size()`
* Use ISO 11146 integration areas
* Add background routines for corners
* Add functions for rotations
* Eliminate old threshold technique
* Use google docstyle for functions
* Explain background and integration areas in notebooks
* Tweak notebooks for clarity

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* use sphinx for documentation
* revise Jupyter notebooks

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* trivial fix for release.txt
* improve text
* remove completed tasks
* initial commit of 07-M2-Measurement.ipynb
* bump version

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* first pass at docs
* General doc improvements
* add routine to draw default figure
* handle symmetric case dx=dy better
* add new definitions and test dx=dy case