README.md: update about the project status

Merge pull request #248 from bzz/go-api-surface

Merge pull request #247 from bzz/doc-update

go doc: minor improvements and clarifications

go: remove Classifier from API

go: reduce API surface

address review feedback

doc: cleanup and simplify

Merge pull request #245 from bzz/initial-cffi-python-bindings

Merge pull request #242 from creachadair/maint

python: expose is_vendor()

python: add dependencies

python: expose language_by_filename()

python: initial impl of bindings using cFFI

Merge pull request #244 from creachadair/installdoc