added a function for debugging cases in which no convergence is reached
minor changes
Merge branch 'master' of https://bitbucket.org/seebaer/pp_dev
added convergence debugging modus to PPall.
--> to get a detailed output for each iteration step, use cdiag=TRUE inside the list() of the control argument. this is not documented yet, because it is for internal use, and will get extended soon.
minor bugfix when model converged in < maxiter steps.