Add additional location information

[Andrew Riha]

For each SNP, add information about the SNP's genomic location:

• Cytogenic location
• Recombination rate at location
• Whether SNP is located in a UTR, exon, intron, LINE, SINE, etc.

This will enable enhanced filtering for SNPs (e.g., location in given region, recombination rate above a given threshold, etc.).

Related to #29