Add OPENMP parallelization to BF population

[lcoombe]

• The solid BF creation was running quite slowly, so added better parallelization

C. elegans tests:	Code version	Time (sec)
Before	107.95
After (8 threads)	36.31

BFs generated are identical:

(synteny) [lcoombe@hpce704 test4]$ cmp ntSynt.k24.w1000.solid.bf ../ntSynt.k24.w1000.solid.bf
(synteny) [lcoombe@hpce704 test4]$