added wojtek's graph stuff
- added forgotten check in LGraph.eq
- removed inheritance; a code can instead now be represent as LGraph<Tag, Label>
Replaced java.util.List with fj.data.List

Other:
- Removed feature where long click menu on code in code editor shows the entire tree of the code. now only shows the root. when there is a notion of a "root code", it is now represented by "^"
- Modified fj.data.List to implement Serializable