Improve qtl.metadata.R

[whimsial]

Currently we perform an overlap join between the scores metadata and a table of T1D hits. While this is correct, it is limited to a specific structure of the table containing T1D hits. We may do better by making this operation more flexible, i.e., conduct overlap join with any annotation table provided chromosome, clump start position and clump end position exist in that table. Thus, users will be able to provide any other annotation that they deem necessary and proceed with the analysis.
We should also allow analysis to continue if no annotation table is provided.