Corrected operator-() in variant_field_ietrator: divide by size.
Included "@brief" doxygen comment for return value in select_if.
Merge pull request #112 from broadinstitute/bh_select_if_doc

Included "@brief" doxygen comment for return value in select_if.
VariantHeader: rename contigs to chromosomes

In order to keep the entire library consistent, the naming must be
standardized.

fixes #93
Merge pull request #113 from broadinstitute/mc_contig_renaming

VariantHeader: rename contigs to chromosomes
VariantHeaderBuilder: add_contig -> add_chromosome
Merge pull request #115 from broadinstitute/mc_contigs_highlander

VariantHeaderBuilder: add_contig -> add_chromosome
Sam: add tests to the public API

Added the following tests:

* unclipped start and stop
* copy constructor tests
* copy assignment test
* tags of types char, int and double
* char_tag when tag is not a char
* string_tag when tag is not a string
* is_missing support for tags

major strides towards addressing issue #4
gamgee.h: one header to rule them all

-One header that gets you all of the gamgee includes (minus the utils)

-For client code (eg., foghorn) where convenience is desired. Should
 not be used within gamgee itself, to cut down on compilation time and
 also to make it possible to still cherry-pick individual headers in client
 code when compile time is critical.

-Avoid having to type silly things like #include "is_missing.h"

-Should be continually updated as gamgee expands (pull requests should
 be rejected if they don't update gamgee.h as necessary)
Merge pull request #117 from broadinstitute/dr_monolithic_gamgee_header

gamgee.h: one header to rule them all
address reviewer comments
create check_max_boundary and inline boundary checks
Merge pull request #116 from broadinstitute/mc_add_sam_tests

Sam: add tests to the public API
Utils: add a zip iterator variadic template
Merge pull request #119 from broadinstitute/mc_zip_iterator

Utils: add a zip iterator variadic template
MultipleVariantReader and MultipleVariantIterator
Merge pull request #118 from broadinstitute/jt_pqueue

MultipleVariantReader and MultipleVariantIterator
When deep copying Sam/Variant records, do not also deep copy the header

Deep copying the headers every time a record is copied is wasteful and
unnecessary, given that headers are immutable (with the single exception
of VariantHeader::advanced_merge_header(), which should be moved to a
builder)
Merge pull request #124 from broadinstitute/dr_remove_header_deep_copying

When deep copying Sam/Variant records, do not also deep copy the header
Move every boundary check to max_boundary check to avoid unnecessary checks