New, self-contained, Windows installer

As discussed in #424 there are several limitations to the current version of our Windows installer, which adds things like `nano` and `sqlite3` on Windows. Most notably it has external dependencies (Python or GitBash) and doesn't feel like the kinds of installers most folks are used to.

This PR allows an Inno Setup Windows installer to be built that executes our existing Python script without requiring a local Python installation. It is also a standard installer that our students will recognize.