Formatting
Add undo and redo directives for history

Not really working how they should though - haven't found a clever way
that they can show and hide themselves so far when used as attribute.
Wouldn't be a problem if used as an element though.
Stuff history plugins into the tab section
Fix wrong file location of redo directive
Formally declare name inside of hist service
Remove headers from history templates
Add an arethusa util object
Add a little xml2json library
Allow multiple retrievers for state
Add and use new text template
Allow multi-retrieval of services in conf
Add some xml functions to arethusaUtil
Add arethusaUtil to index
Add example treebank file
Allow multi-retrieval in state
Parse from treebank template in tokenRetriever