buildbot: build documentation, add nightly upload of master docs, other tweaks

* master.cfg: Add a "build-docs" builder to test generation of HTML and PDF
  docs into the commit checks.  With nightly=true property, upload generated
  docs to a static dir on the master.  Run from a NightlyScheduler.

  Add the properties from the internal worker config to the buildbot
  BuildSlave properties, so they're visible in the web UI. Filter through
  a workers2publicprops helper, to whitelist allowed props.
1 file changed