This commit moves all html/markdown editor logic to the ribbit library.
Submodule tracks https://git.evilchi.li/evilchili/ribbit.git.
The dist files in static/ are committed copies; the submodule
provides source access for development.
We use pre_format and pre_build slam hooks to ensure the submodules are
initialized and updated correctly, and to perform the dist file copy.
This commit imports the latest source of the pwic module directly
and modifies it just enough for it to be an importable module.
Source: https://github.com/gitbra/pwic
