Rewrite LibSVM in scala - optimize and simplify the code

[strelec]

The code currently sits at around 3000 Java code lines. I believe I can make that to 1000 lines of scala, with even better performance, since the current Java code is just a line-to-line rewrite from C.

To ensure correctness, make an unit test that will compare the outputs on all the datasets.

[strelec]

After this is done, consider extracting it to an external library as someone else could benefit from that.