* now use optim rather than nlmfor minimisation in single index and
smooth coefficient models
* fixed bug in klein-spady objective function
* regression standard errors are now available in the case of no
  continuous variables
* summary should look prettier, print additional information
* tidied up lingering issues with out-of-sample data and conditional modes
* fixed error when plotting asymptotic errors with conditional densities
* fixed a bug in npplot with partially linear regressions and 
plot.behavior='data' or 'plot-data'
* maximum default number of multistarts is now set to 5
* least-squares cross-validation of conditional densities uses a new,
 faster algorithm
* new, faster algorithm for least-squares cross-validation for both 
local-constant and local linear regressions.
   The estimator has changed somewhat: both cross-validation and
   the estimator use a method of shrinking towards the local constant
   estimator rather than the standard ridge approach that shrinks
   towards zero
* optimised smooth coefficient code, added ridging
* fixed bug in uniform CDF kernel
* fixed bug where npindexbw would ignore bandwidth.compute = FALSE and
   compute bandwidths when supplied with a preexisting bw object
* now can handle estimation out of discrete support.
* summary would misreport the values of discrete scale factors which were
   computed with bwscaling = TRUE
