Also run our tests
Set Git attributes for BAM files in the repository
Add help command and --version options

Rearrange version.h inclusion -- only bamtk.c should #include version.h
so that only one translation unit needs recompiling due to changes in it.

Separate samtools_version() and hts_version() so that they can be displayed
in a more user-friendly way where appropriate.  (--version-only uses
punctuation other than %s:%s as it's likely to be embedded in executable
paths and ":" is a shell semi-metacharacter.)
Write samtools --help output to stdout
Ensure $HTSDIR is used by "make test" too
Remove bcftools, SAM, and VCF sections from man page

The bcftools sections are moving to bcftools.1 in the bcftools project
to be alongside the code they document, while the file format summaries
are moving to htslib, alongside the code that reads/writes them.
fall over if a bed file given as an option cannot be read