+ add new filtering options to vcf-compare-gt

  Allows for specification of filter modes ("filtered", "unfiltered",
  "both") on a per file basis to control which variants are visible.
tokenizer cleanup
move InputStream and StreamHandler to io lib
key-value pair parser
add renameSamples(...) to Vcf::Header
add ability to rename samples to vcf-compare-gt
Merge remote-tracking branch 'origin/filter-flag'

Conflicts:
	src/lib/ui/VcfCompareGtCommand.cpp
add --output-file option to vcf-compare-gt