* Removed modules we don't seem to use any more.
* Went through *all* the imports (including 'from X import Y') and
checked every module was one of: builtin, stock in win32 python
3.7.7 or a known dependency of another we do list.
* As we still have the sqlite3.dll hack in setup.py I've only
specified: +py2exe>=0.9.3.2
* certifi==2019.9.11 to work around py2exe issues the current latest
* keyring==19.2.0 to work around py2exe issues the current latest
This still needs testing to see if it's enough to setup an
only-just-installed Python-32 of 3.7.7
