Start to wrap the dagreD3.Renderer
Remove dagreRenderer again

Still valuable to keep in the history as debugging with it solved a few
issues resolved in the next commits.
Don't rerender the tree on style changes

Only update the directives. Right now they are replaced, this can
probably done even more efficiently by just updating their style.
Destroy childScopes in dependencyTree

Closes a massive memory leak - we were building up childScopes like
crazy. A long annotation session build up thousands of useless
scopes...
Clear headWatches also

Code for this was already there, but we failed to actually store the
childScopes.
Refactor scope destruction in dependencyTree
Refactor and fix style resets for labels and edges
Refactor in depTree
Use state eventing only in dependencyTree
Hack-fix weird behaviour on tokenRemoved
Put token class directly on the directive
Avoid color flickering in dependencyTree
Merge pull request #322 from latin-language-toolkit/tree_performance

Huge boost of tree performance and closing of a severe memory leak