Feature/submodule git

Created by: chris

• Initial submodule structure

• Adding some documentation

• Testing full creation of git submodule

• Adding stub for parsing git modules

• Finishing up submodule parsing and refactoring some regular expressions.

• Lots of fixing and a little refactoring

  1. Refactored Graphviz writer to handle creating subgraphs and building them into a root document
  2. Fixed equality tests in Git objects
  3. Created integration test for raw git input through Graphviz document generation