* Add github.c and github.h

* Implements get_github_release_notes()

* Remove unused variables

* Fix circular dependency on tplfunc_frame

* Remove predeclaration of tplfunc_frame
* tpl_register_func accepts pointer to void instead
* tpl_register_func sets maximum number of arguments
* Frame is generated within tpl_register_func

* Improve template function error handling and return/output management

* Remove redundant extern statement

* Include github.h and template_func_proto.h in core.h

* Expose get_github_release_notes_tplfunc_entrypoint function to template engine

* Add template_func_proto.c and template_func_proto.h

* Replace free() with guard variant

* Fix test_template::test_tpl_register_func

* Fix tests

* Fix tests

* cmd should be at least PATH_MAX in size.

* Magic number caused failure to install conda with a long installation path

* Implement get_github_release_notes_auto function that bases release note data off test contexts

* Disable overwriting releases by default

* Add automatic release note generation function call to release_notes.md.in

* Fix test_tpl_register_func()

* Add enough space for tar command plus a path

* Fix circular include

* Github functions do not require access to core.h anyway

* Add comments to union

* Update README to mention template function availability

* Add EnvCtl structure
* Add runtime checks to avoid running all the way to the end only to be met with a configuration error.
* Rename GITHUB to GH

* Development docs pre-rough-draft