2010-06-02  Rajarshi  Guha  <rguha@Macintosh-5.local>

	* R/balance.R (balance): Added a method to generate balanced fingerprints, which have 
	50% bit density, but are 2x the size of the input fingerprints.

	* R/bitimp.R (bit.importance): Added a function to evaluate the importance of each bit
	in a binary fingerprint in terms of the Kullback Liebler divergence between a set of
	actives and a background collection.
	

