Adds test for usage messages for bcftools and all subcommands

Parses usage output into sections and looks for usage, version, and commands sections
with somewhat loose regexes (biggest assumption is that section headings are the only
non-whitespace at the beginning of lines, which is currently true)

Dispatches a test for every subcommand found in the raw `bcftools` output

Verifies that the "Usage:" line mentions the name of the program [+subcommand] being run
Relaxes parsing regexes slightly (based on parsing samtools output)
Merge pull request #20 from sm15/feature/subset_options

cleanup of some things after the renaming of subset to view
Merge pull request #18 from wtsi-hgi/feature/test-usage

Adds test for usage messages for bcftools and all subcommands
stats: Updated to work with modified htslib/bcf_regions; More tests for -t/-r
add new options to vcfview to select/exclude phased sites

option -p/P added to vcfview to select/exclude sites where all
samples are phased.

function bcf_all_phased returns true if all samples are phased.
haploid genotypes are considered phased, ./. => not phased,
.|. => phased, 0/1|2 => phased

tests added for these options. added a few sites to the view.vcf
test data so that the options could do something useful in the
test. updated output of other tests to reflect this too.