Implement Graph Coloring Problem

[abeham]

The problem has been implemented in the MemPR branch together with benchmark instances and needs to be integrated into the trunk.

[abeham]

r15050:

• Integrated graph coloring (GCP) into trunk
• Additional Changes to branch version:
  • Added parameter BestKnownColors in addition to BestKnownQuality
  • Added a best colors for the default instance
  • Adapted Analyze() to output best found solution and fixed tracking of "Best Solution Colors" and "Best Solution Conflicts"

[jkarder]

Reviewed r15050:

• the project GUID within the project reference to HeuristicLab.Encodings.LinearLinkageEncoding-3.4 is wrong; please remove and add the project reference again
• problem instances / import:
  • some instances cannot be imported; the parser does not handle empty lines
  • rename Parser to GcolParser
  • the parser should already fix the node indices; currently this is done by the GcolInstanceProvider
• GraphColoringProblem.FitnessFunctionOnValueChanged should not always set the best known quality to null, but instead calculate it (as it is done in Load) if possible

[abeham]

r15172:

• Implemented review comments
• I had to restructure the parser to a greater extent because I found out that some instances defined nodes without edges (which I decided to filter)
• I added a unit test that loads all instances
• I also added export of instances

[jkarder]

Looks good, thanks!

r15173: minor formatting

[abeham]

r15217: merged revisions 14412, 14475, 14476, 14659, 14660, 14663, 14779, 14780, 14912, 15050, 15067, 15069, 15079, 15162, 15166, 15172, 15173 to stable