Added coloring profiling code; Sped up coloring step

[brandon-mork]

Added profile option to generate_coloring.py CCAlgorithm and associated profiling code to profile each step.

Fixed unnecessary calls to g.get_max_id(), which in turn was calling max(). This cut ~30-40% of the run time for each coloring step.

Changes:

• lib/coloring/generate_coloring.py
  • Added profile field to CCAlgorithm, defaults to false
  • Added profiling code to print stats for each step of coloring
• lib/coloring/basic/check_tree_depth.py
  • Added field to keep track of max_id
  • Replaced calls to g.get_max_id() with new g.max_id field
• lib/coloring/generate_coloring.py
  • Changed profiling code to default to off