Split txtdump.*, part 1

Split txtdump.*, part 1

- Move routines to print various data structures to the file that
  declares the data structure, mostly to topology/.
- Rename pr_header() to pr_tpxheader() to clarify its use.
- Remove unused pr_commrec() and some commented-out code.
- Remove unnecessary uses of txtdump.h.

This helps avoiding dependency cycles coming from this (because in its
old form, any code that wanted to use these routines for, e.g., debug
output, would need to be above all the data structures for which this
printing was supported).  Also, it makes it easier to find the code that
needs changing because of a data structure change easier when it is
close to the declaration of the data structure.

Follow-up commit will move txtdump.* out of fileio to resolve existing
cyclic dependencies, but split that into a separate commit to keep the
size manageable.

Change-Id: I2665f6d25cd095f4c7d11d32bcaec38601ff8d8b