This release includes all current (1.21.14) changes made to the 1.21.x series.

Enhancements:
-------------

* Configuration is local, passed via config argument.  No more global config.  #953
* Created Python API in conda_build/api.py #953
* Separate build folders per-build to allow parallelism #953
* Add locking to allow safe parallelism #953
* Add build flag to turn off separate build folders (--no-build-id) #953
* Much greater test coverage across all modules #953
* Add CONDA_BUILD_STATE variable that reflects RENDER, BUILD, or TEST state of build #1232
* Add support for HG_ variables in meta.yaml templates (for hg repos) #207 #1234
* Add source_files test argument in meta.yaml to copy files from source into test #1237

Bug fixes:
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* Fix error converting linux to win packages due to python version mismatch #481
* Fix infinite loop that occurred with circular dependencies being built #953
* Improve test data structures to allow profiling with pytest-profiling #953
* Fix version sorting in pypi skeleton generator #1238

Restructuring:
--------------

* CLI scripts have been gutted and moved to conda_build/cli.  Content from them is in
  conda_build, in scripts without main_ prefix.  #953
* Skeleton generators have been broken out of main_skeleton.py, and consolidated into
  conda_build/skeletons.  The contents of this folder are examined at runtime for pluggability.  #953