New feature set: distances b/n AA's

Counts occurences of AA pairs of distances up to n.
Vector = [B1, B2, B3, B4, P1, P2, P3, P4, D1, ...]
where B2 := number of occurences where distance from an
AA B to to the next B is 2.
Merge branch 'master' of https://github.com/hacheson/svm-project