Multi-phenotype file save in stats. Changed prototype calls.

Changed ped_close to add one parameter. See libs/bioinfolibs/bioformats/ped/ped_file.c
Added argument "--phenotype-field=<string>"
Added variable-grouping and control-case considerations.
Merge branch 'next' of github.com:opencb-hpg/hpg-variant into multi-phenotype-stats

Conflicts:
	src/vcf-tools/merge/merge.c
	src/vcf-tools/stats/stats_options_parsing.c
Finished implementation of multi variable stats
Merge branch 'next' of github.com:opencb-hpg/hpg-variant into next
Merge branch 'multi-phenotype-stats' into next
VCF statistics grouped by phenotype