Add Annotations

[shintoo]

The user should be able to annotate nodes (maybe branches?)

Or, the user can simply annotate the canvas, and it moves as the canvas is panned around; the only issue there being when the tree is updated, the annotation would not automatically move to where it should be (e.g. if Passeriformes is annotated, then a node addition moves that node on the canvas, the annotation would now know to follow the Passeriformes node)

And for that reason - I am more in favor of simply annotating nodes.

(This probably depends on Canvas clicks being fixed)