Refactor code

- made a routine in morrislib to retrieve genelists.
- updated scatter plot and maplot routines to use the genelist routine to retrieve data.
- genelist routine can optionally remove NAs and filter out low-expression genes.
- fix database gene count retrieval to work for multiple datasets, not just two at a time.
  Doing a full join in R an opposed to in MySQL is much, much faster.