Keine Ahnung warum.
Optimierer-Bug??

- inheritance for CNodeConv, preparing for PConv

clearly distinguish index k,j,i from reference x,y,ni,r0,z1,...

constructors are now CNodeIva( PVar, PRef) and CNodeCev( PRef, PTree )
CRef has changed meaning: it has no more relation to CVar;
it just represents a subscript set [k,j,i]

in CNodeIva constructor an ugly workaround

not fully understood why error had no effect

therefore autoreconf'ed
setConv moved to NCurveFile

TODO:
- get rid of last switches
- simplify tree_conv
- remove typ by duplicating tree_conv
- delete typ altogether
- move parameters to subclasses

execution mechanism still through switches