Tool should be generally similar to the compilation DB tool, and it should:

• Depend on all object files
• Contain a basic implementation of a graph class to model the graph we'll generate
• Integrate directly into SCons
• Contain library, file, and symbol dependencies, using an architecture that will support adding new node and edge types into the graph.

This commit should also include:

• Test coverage for all operations "above" the SCons integration.
• README or an extensive comment describing architecture, design, and how to run tests.
• License headers for Apache2