Fixed graph features

- Common graph code made into a method.
- No longer needs the user to pass in the ga for graphing.
- Changed graph attribute from class to object.
- Added ga to the graph object as an attribute on initialization to avoid needing to pass it in every time you graph.
- Capitalized database/graph classes.

src/run_testing.py

@@ -20,4 +20,4 @@ ga.evolve()
 
 ga.print_population()
 
-ga.graph.lowest_value_chromosome(ga)
+ga.graph.lowest_value_chromosome()