minor change in header
changed ->missing to ->missingOffset
read/write .dosage like .missing, sharing code
code to calculate and store dosages on imputation
new functions to read and use genetic map (Oxford style)
add dosage handling, commandLine storing, genetic map handling
restructure a bit and add pbwtGeneticMap.c
correct hreshold for imputation from 0.2 to 0.55
write sites.freq in option -sfs, and add code to read reference site frequencies and use them in genotypeCompare
fix merge conflicts
Merge branch 'master' of github.com:richarddurbin/pbwt into feature/test_referenceImpute