1.04 -- Added PTBmu.gen and PTBmn.gen method for repeated disturbances
	Fixed a bug in PTBu for size<>1
	Minor documentation

1.05
-- Added a framework for discrete perturbations using a reclassification matrix
(PTBdiscrete,reclass.mat.diag)
-- Updated default perturb options to detect discrete variables and
   use appropriate method
-- Added plot method for perturb.summary
-- Added built-in support for perturbing Zelig models and plotting and summarizing
   the results

1.06 
-- Add plot(summary()) 
-- Support for Zelig strata

1.07
-- Added vignette

1.08
-- Added HTML methods for R2HTML support

1.09 
-- Change object name to "sensitivity", to reduce conflict with perturb module
-- Performance enhancements
-- Fixed bugs using codetools

1.10
-- Moved citation file
-- Added vignette (really)

1.11
-- Workarounds for Zelig 2.52 changes. More sophisticated analysis of zelig formulas.

1.12
-- Code reorg and comments

1.13
-- Makefile  and .Rnw stub to force vignette to be indexed
-- Check types of sechol() input

1.14
-- Real vignette
