Merge pull request #24 from erwinwinder/master

Impute2
Small refactor genotypeData
ModifiableGenotypeData work in progress
Merge with erwin
Merge pull request #26 from PatrickDeelen/master

Small refactor genotypeData and merge erwin
ModifiableGenotypeData

Needs tests
ModifiableGeneticVariantIteratorTest
Added equals to sample
Modifiable Genotype data work in progres + some tests
Modifiable genotype data. Ref updates works + tests, fixed iterators
Modifialbe genotype data update ID works + tests
Dosage for modifiable genetic variant
Improve javadoc
Modifiable genotype data completly tested and working
Refactor genotype data reader formats
Fix reading plink files with the undocumented I and D alleles
Minor refactor
Minor test cleanup
Extra test ped map
ModifiableGenotypeData can remove variants, fully tested