BUGS/ISSUES:
 
  use numDeriv library hessian() function instead of nlme::fdHess?
(use nlme::fdHess to avoid loading whole package?)

  turn off Hessian calculation for profile fits??

  should print warning immediately if convergence fails

  some weird stuff with returned fit from found-better-fit profile --
treating profiled value as fixed ...

BUG:   order of parameters matters for L-BFGS-B

  adjusting parameter vectors for lower, upper, parscale, ...
    when some params are fixed ...

  sort out names BS -- when can we safely remove names?


TO DO:

more documentation -- especially S4 methods!
   especially:
     profile
     plot profile
     confint

catch/interpret more error messages?
  (try to filter last.warning?)

add DIC to IC tabs?

WISHLIST:
start as FUNCTION (i.e., self-start)
analytic derivatives
relist
subset
predict (feasible for formula arguments
          if we know the MEAN of the relevant distribution?)
plot.predict
drop1, add1, etc.
link functions ("identity","log", "logit", etc.)
clean up/argue about data handling: closures etc. etc. etc...

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)