various updates

Implemented some bug fixes suggested by Ben Bolker.  Implemented more
efficient likelihood calculations into functions other than functions
used to maximize likelihood.
various updates

Added zero altered negative binomial distribution.  Added additional
dwell time distributions:  geometric, logarithmic, pospoisson, which is
slightly different than shiftpoisson in that it redistributes
probability mass from 0 to the remainder of the support.  Made a few
things more efficient and fixed a couple of plotting bugs.
Merge
general cleanup
Merge branch 'master' of github.com:bbolker/move.HMM into HEAD

Conflicts:
	DESCRIPTION
	NAMESPACE
	R/HSMM.plot.R
	R/move.HMM.mle.R
	R/move.HSMM.mle.R
	R/print.move.HMM.mle.R
	R/print.move.HSMM.mle.R
	R/rwrpcauchy.R
	Read-and-delete-me