-  allow  ic = <number> ==> something between AIC & BIC, or (ic = 1 :more
       overfitting than AIC)

- For knot selection: allow setting final number of knots (after knot selection)

- predict.cobs() should have a 'deriv = 0' argument {as predict.smooth.spline()}
  and deriv in {1,2,3} should work.  This is closely related .splValue()
  etc, see below.

- For the case 'lambda < 0' (i.e. search over several lambdas),
  we can become *much* faster in matrix creation, since alle constraint
  matrices are *not* dependent on lambda at all!

- allow  constraint = c("increase", "convex")   i.e., *BOTH* constraints!

- When determining optimal lambda (via 'ic'),
  allow a "+ 1 S.E. - rule" instead of simply taking the arg_min
- ditto for knot selection

- Add details and examples (!) for the intermediate/ auxiliary functions
  qsbks() and drqssbcs(), in  man/qbsks.Rd & man/drqssbc.Rd

- need examples with degree = 1
  and several other values of tau
  also extreme cases of interpolation and global linear/quadratic

- want to have examples of all constraints, including "periodic"
  and 'pointwise' (now done) and (periodic + pointwise) etc

- src/splines.c is UN-needed in R --- rather use library(splines) !!
  ------------- now have .Call(*) there instead of .C() here.

   partly done: now use .splBasis() and .splValue() <<<<-- R/splines.R -->
   --> tests/spline-ex.R  shows how .splBasis() can be done via library(splines)

- lambda < 0; for each pp.lambda, instead of (only) $sic,
  return both components : Log.lik. and p[lambda] ( = k[lambda] ), the dim.



------------------------------------------------------
Old 'TODOs' which are done (here for reference only):
==========            ====
------------------------------------------------------

- add the three interesting real data examples from the COBS "paper".
  in the paper, they say that S-plus code for these examples is available
  as well. --> see also ./inst/scripts/ and ./tests/

- example(cobs) gives lots of warnings;
  the upper and lower quantiles are not plotted (not properly computed ??)

- man/cobs.Rd  needs the current reference list !

- cobs() should keep its call and return an object of class "cobs".

  Then print.cobs(), summary.cobs(), predict.cobs() and plot.cobs() should
  be designed!
	---> this is now done  { --> old & original code in ./R/cobsOld.R }

- added some documentation for qsbks() and drqssbcs(): man/qbsks.Rd & man/drqssbc.Rd

- cobs() should get an 'keep.data = TRUE' argument as smooth.spline()