Split txtdump.*, part 2

Split txtdump.*, part 2

Move basic txtdump.* to utility.  To avoid introducing more cyclic
dependencies, move some contents closer to declaration of the types
being dumped:
- Move pr_inputrec() to mdtypes/inputrec.*.
- Move pr_*() functions operating on vectypes.h types to math/vecdump.*.

One additional cycle suppressed for now; on the other side, this removes
nearly all pbcutil -> fileio and topology -> fileio dependencies,
getting us closer to removing those cycles.

Add basic comments for remaining txtdump.h functions to avoid Doxygen
warnings.

Change-Id: I8ec5b34f6d5af8e63f9716e782943e75cb06b5b5