Merge with qvalue package

The functionality in fFDR is intended to be combined with the qvalue package. Some notes:

• This should be done only when/if qvalue is converted to S4 and unit tests are added
• One package can contain multiple vignettes, which means there will be a separate vignette for the use of fqvalue as opposed to qvalue
• This will likely be done on a branch of qvalue in the private repository