dec 2011 -- compare permutation performance with regressOut to use of
	covariates
Oct 2010 -- need to allow the eqtlTestsManagers to be "indexed" by GenomicRanges instances
	so that lookups can be more driven by genomic contexts, less by
        character matching
Aug 2008 -- removed SQLite snp location metadata, substituting a
    structure based on the SNPlocs.Hsapiens package
---
Aug 25 2007 -- bug in plot_mlp -- if a trans analysis is done, 
attempts to plot gene on current chromosome ... -- seems fixed, 28 aug,
  but check for whole-genome as in mouse example

Apr 10 2007 -- need more general framework to deal with various
 representations of genotype data (particularly those obtained
 through multiple SNP chips)

Oct 12 2006 -- it would probably be useful to bind the SNP location
 data into the racExSet

Oct 12 2006 -- need to investigate the SQLite representation options

Oct 31 2006 -- need to get rid of the deparsing of the fitter argument.
   define a GGfitter class extending function and condition on its presence
   -- this seems related to Martin Morgan's concern for empty classes.
