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This tag adds a few small changes in response to the domain review. As follows:

* Added `environment.yml` for conda installation
* Shared outlet basin pixels now prioritize the most downstream basin
* watershed.network now returns pixel centers, rather than upper-right corners
* Improved the support of depression filling when conditioning a DEM
* Fixed a bug in the assignment of basin data properties

This commit adds a variety of features in preparation for the v1.0 release. The largest updates are to the segments class. In summary:

File format drivers:
* Exposed file format drivers when saving rasters and features
* Added utils.driver module

Backend improvements:
* Most class properties are copies
* Raster values are read-only views
* Validation methods do not copy whenever possible
* Consolidate NoData logic in NodataMask class

Misc quality of life:
* Set license to gplv3
* Added spatial option to Raster.from_array
* Added nodata casting option to Raster.from_array
* Add "burned" alias to severity
* Enhanced broadcasting in g14
* Suppress log(0) warnings in g14
* check_flow option in watershed

Segments:
* Now tracks segment connectivity
* Add flow-continuous filtering
* Add functions to locate terminal outlets
* Add function to build terminal outlet basin raster
* Add basin and outlet export (as polygons/points)
* Add omitnan options to summaries (also to s17 variables)

This commit completes the migration to pysheds, and represents a minimal working version of the pfdf package. Key updates include:

* The Segments class has been refactored for pysheds
* Segments class now calculates earth system variables needed to run probability, volume, and combined hazard models
* The staley2017 module now solves for both probability and accumulation
* Simplified the calculation of earth system variables in staley2017
* Added a utility module to convert between various types of slope metrics

This commit migrates the codebase to use pysheds instead of TauDEM and ArcPy. Key points include:

* Package is now fully open source
* All dependencies are Python packages - conda install no longer necessary
* The `dem` and `stream` modules (using TauDEM and ArcPy) have been replaced by the `watershed` module (using pysheds)
* Raster backends have been consolidated into the Raster class

Note that this tag intentionally breaks the `segments` and `models` modules, which will be refactored over the next 1-2 tags.

This tag adds in two hazard assessment models. These are (1) the debris-flow potential sediment volume model of Gartner et al., 2014, and (2) the combined relative hazard classification model of Cannon et al., 2010.

This tag adds functionality to implement the logistic regression models from Staley et al., 2017

This tag provides much of the core infrastructure for the pfdf package. This includes:

* DEM analyses,
* Burn severity operations
* Stream segment management
* poetry/conda installation
* Tests of nearly all functionality, and
* A consolidated backend

Notable backend features include:

* typing
* raster metadata management
* nodata masking
* user-input validation