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
Explicit support for haploid positions in VCF stats and mendelian errors checks
Support for loading structural variants from VCF v4.1 files
VCF statistics grouped by phenotype
MAF filter removes records with less MAF than the specified
VCF stats working both providing a column variable or not
Merge branch 'next' of https://github.com/opencb-hpg/hpg-variant into next
Initial code for Annot