to write output, you would usually just use the print builtin
since commanders are just lua custom commands but this does not
consider the fact of pipes or other shell operators being used
to redirect or whatever.
this adds readable/writable "sinks" which is a type for input
or output and is currently only used for commanders but can be
used for other hilbish things in the future
- get docs properly for hilbish module and its interfaces
- deal with negative numbers causing yaml metadata parsing to fail
- change from index to _index to match hugo
changes the actual file format of docs to markup since that's basically what we have been
using in the first place.
the docgen command has been modified to write markdown headings with the function name and
yaml metadata for easy consumption by hugo for the website.
all other docs have been moved to markdown as well this is the main reason this is a "breaking" change
users will have to reinstall hilbish (task uninstall and task install) to remove the old plaintext docs