fix sqlalchemy regression
Merge remote-tracking branch 'arskom/2_9' into 2_9
import headers' namespace to tns when different
Merge branch '2_9'
some harmless cleanups here and there
add optional root support to WsgiMounter
minor.
add missing host_matching flag to werkzeug mapper.
docstring update.
minor.
add yaml support.
make werkzeug rule endpoint assignment template friendly.
remove needless loop.
minor.
Changelog & readme update for Yaml.
Split dict logic in DictDocument as ``HierDictDocument`` and ``FlatDictDocument``.
add support for optionally ignoring missing values to *DictDocument.
fix pyyaml url in readme