Ensure joins between annotation and scores metadata are always unique.

[whimsial]

The current code is not future proof because new labelling scheme for the genome-wide trans scores allows for duplicated scoreids. In fact, we store as many duplicated scoreids as there are individual scores contributing to each genome-wide trans score. Therefore, joins with annotation tables may fail.

To address this we need to extend the original key to also include locus start and end position by changing these (and similar) lines:

trans-qtls/qtl.metadata.R

Lines 51 to 52 in 8fd37aa

	setkey(transqtl.loci, scoreid)
	setkey(trans.genome.wide.scoresinfo, scoreid)

to:

setkey(transqtl.loci, scoreid, x.startpos, x.endpos)
setkey(trans.genome.wide.scoresinfo, scoreid, x.startpos, x.endpos)

@dlipschu, we need to check that this change does not affect your results.