[CVS ci] PMC-data-1

[Leopold Toetsch]

This is the first of some changes, before pmc->data can be moved
into the PMC_EXT structure.

While digging through the classes and
  :perldo s/(\w+)->data/PMC_data($1)/g
some notes are accumulating:

- CSub seems to be unused and is AFAIK obsoleted by NCI
- Pointer should probably also get deleted. It seems to be used in
  rx.ops only, UnmanagedStruct could be used instead.

Comments welcome.
leo