fixed ineffeciency when calculating only the auto correlation
changed the logical ifs for the cross correlation decisions
changed the logical ifs for the corsscorrelation decisions
added MPI to jackknife 2pcf
changed the functions to only calculate the cross pairs between data1 and data2 for consistency with the other versions of pair counters
fixed typo in jackknife code
Merge pull request #37 from duncandc/develop

Develop