Changed `isnan()` logic in `grid_cell.hpp` to facilitate MSVC compilation.
2.2.8
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Release for Zenodo DOI.
2.2.7
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Fixes some compilation issues for Windows caused by MSVC not having M_PI by default.
2.2.6
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Fixes some compilation issues for Windows.
2.2.5
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Travis-CI deployment to Github works.
2.2.0
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Includes D4 flow routing, depression filling, and depression breaching Uses `chrono` for timing instead of `sys/time.h` Includes Windows compatibility improvements