Merge branch 'master' into pull_143
improved customizing markup parsers

 - class-based markup parsers
 - rename pybb.markup_engines to pybb.markup
 - moved all markup related function to pybb.markup module
 - use new string-based defaults for PYBB_MARKUP_ENGINES, PYBB_QUOTE_ENGINES and PYBB_BODY_CLEANERS
 -more markup related tests
 - remove global pybb.util module variables: MARKUP_ENGINES, QUOTE_ENGINES, SMILES_DICT
upgraded embedded markitup library
updated default embedded ajax_csrf script
Merge branch 'master' into pull_143
improved class based markup engines

- engines splitted to separate modules to prevent requiring not used libraries (bbcode/markdown)
 - improved deprecation warnings
 - actualized docs
 - use global variable for caching markup and quote engines
fixed test requirements
merge with hovel's commits