remove graphics lib
add isFiltered method to vcf entry.
add allButSamplesToStream to vcf entry

prints everything but sample data
SampleData class updates:

1) use hash instead of tree for caching genotypes
2) add "appendFormatField / appendFormatFieldIfNotExists"
3) add sampleToStream to print a single sample
test allButSamplesToStream (Vcf entry)
make genotype comparator keep track of entries
include boost source instead of tarball