Use java-math-library for prime factorization

[axkr]

Use https://github.com/TilmanNeumann/java-math-library for prime factorization.

Flag Config.JAVA_UNSAFE is set to true to allow usage of java.misc.Unsafe

Flag Config.EXPENSIVE_JUNIT_TESTS can be used to do long running JUnit tests.

Merged to master

[TilmanNeumann]

Hi, I just added a new constructor to class CombinedFactorAlgorithm that allows to turn off sun.misc.Unsafe features. This should help you to obtain better performance even if Unsafe is not supported by the platform. Due to my tests, the performance loss not using Unsafe is only about 10%.