Opt fixes and specifics strategy simplification

[d-michail]

Main changes

• Simplified the specifics strategy interface and implementations
• Fixed a bug when using the FastUtil map classes (we were using reference equality instead of .equals())
• Added a graph implementation specialized for Integer vertices which uses the more specialized integer keyed map implementation of fastutil.
• Moved all classes using FastUtil into a separate .fastutil package.

@jsichi I am having some trouble naming the graph classes. I used the pattern FastutilMap - IntegerAny - Graph where the Integer is the vertices type and the Any is the edges type. Does this make any sense? What about the first part? Should I shorten it, remove it, etc?

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[jsichi]

How about this convention:

• FastutilMapIntVertexGraph (implies edge type is unrestricted)
• FastutilMapIntVertexLongEdgeGraph (edge type is specialized to long)

(Let's follow the fastutil typename convention Int, Long, etc)

For GraphSpecificsStrategy, acronymization to GSS is probably called for.

[d-michail]

I renamed the classes, per your suggestion. I also moved a few tests from the new isomorphism package to the slow tests category, because the test phase was getting slow again.

[jsichi]

Thanks!