Bump version to 0.7.4.rc1
Add various empty __init__.py files to make setup.py happy
Fix PyPI uploading in the release fabfile

This is still untested, but I believe this will work.
Start work on using the GitHub releases API

Most code is copied from SymPy-bot. The release uploading is not implemented
yet.
Optionally save the GitHub token to a file
Make it more clear when mailmap_update has errors
Update .mailmap
Don't name the docs zip file "nozip" (issue 3988)
Update tests list in setup.py
Do all tarball testing before building the docs
Update fabfile whitelist
Revert "Do all tarball testing before building the docs"

This reverts commit 029d838468fa95b7019070c3b597be87f3b282d7.

The tarball check runs locally, so it needs to go last.
Don't recreate the exception (it loses information)
Change GitHub API code to use the requests module
Warn/error when requests is not installed

This lets the release work without requests, except for the GitHub uploading.
Finish code to upload files to GitHub releases
Include the sizes in the GitHub release table
Remove unnecessary comment
Fix slow tests in python3.
A simpler, more limited fix to issue 4111.

Just change a few stray invocations of iteritems() to items(), in
order to be compatible with Python3 and consistent with previous
changes for supporting a Python2/3 unified source.

	modified:   sympy/core/compatibility.py
	modified:   sympy/core/tests/test_compatibility.py
	modified:   sympy/functions/elementary/trigonometric.py
	modified:   sympy/polys/polycontext.py