function to check sample IDs across geno/pheno tables

[jhawkey]

helper function to check that you can merge the geno/pheno files together - do all the sample names in one exist in the other? print a warning if samples are missing from one or the other table

[katholt]

need helper function e.g. compareGenoPhenoID

• input = pheno data frame, name of the ID column (otherwise take first column, or try to find 'sample' or 'biosample'; same for geno data frame
• compare the sample IDs, make a list of unique entries that appear in both
• report the number of overlaps and uniques
• return copies of geno and pheno data frames that each contain the overlapping samples only

This helper function can be used by getBinMat and lots of other functions as a starting point

[jhawkey]

Made a simple function to check sample ids, inside helpers.R 23bf22b

Still needs to be made more generic to deal with different options for column names