BUGS/ISSUES:

  BIC conflict with nlme (S3/S4)

  calling profile, etc. on mle objects
created inside a function doesn't work

  should print warning immediately if convergence fails

TO DO:
  more documentation

WISHLIST:
analytic derivatives
relist

document argument handling:

  start must be a named vector or a named list
       [OR?? inherit from parnames(minuslogl)?]
  if start is not a list (i.e. a numeric vector)
  set vecpar TRUE
  convert start to a list

  if missing and default.start is TRUE use formals(minuslogl) 
  [why?]

