#7 Parsing changes. see detailed message

- Node statements are now being parsed
- Types used when parsing are becoming more like an AST
- Cleaned up dot.fs
Readablity
Deleting experimental code
Correcting spelling mistake
Deleting unused functions
Changed depthFirst's type sig to be more generic
Fixed node smt parsing bug

- Node statements that end with a semicolon are now parsed correctly
Support for Edge attributes. closes #7
Generic func to fold over statements

- Abstracted the shared part of getNodes and getEdges