Merge branch 'master' into ng/master

Merge branch 'master' into ng/master

* master:
  contrib: check-html: pass flags to rst2html invocations
  contrib: simple improvements to check-html
  coverage: check-html can be used recursively
  tests: tests for stuff in contrib goes in 'contrib/t'
  recursion: support user-defined recursive targets
  tests: rename 'recurs*.sh' to 'var-recurs*.sh'
  tests: minor improvements to 'recurs*.sh'

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>