R CMD check is too slow for CRAN

[Jason Vander Heiden]

Check currently takes 11 mins ion CRAN’s windows devel server, which is over the 10 min limit. We need to reduce the check time. If build/install is included in this timing, which it might be, then removing the BioC dependencies (see #97) may be enough. testMRCA and testEdges are slow, so we could maybe improve their performance. Otherwise, we may have to split the package (eg, by moving some stuff into dowser).