Before this CL, the web archive had two folders: "public" (which
contained web demos written in C++) and "filamentjs" (for the barebones
WASM).
After this CL, the web archive will instead have "dist" and "docs". The
dist folder will have the WASM and accompanying JS file, while the docs
folder has the tutorials and their accompanying demos.
If your machine has Python 3 installed, then "build -ap webgl" will
attempt to generate the JavaScript docs. If Python 3 isn't available,
this build step will be skipped. Note that our Kokoro macOS machines
already have Python 3 pre-installed.
Also removed the pipenv file to simplify the Kokoro Python environment.
Fixes#394.
28c56eb354