Rewritten nparncpF and associated fitted, plot, lfdr methods; 
minor updates to plot.nparncpt;
rewritten dtn.mix as a dispatcher. 

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/pi0@350 edb9625f-4e0d-4859-8d74-9fd3b1da38cb
minor debug of dtn.mix.R

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/pi0@351 edb9625f-4e0d-4859-8d74-9fd3b1da38cb