Also bytes aren't bits

because the latter no longer includes whitespace

this is allowed because objects no longer need to consume leading whitespace
and all delimiter rules have been made explicit.

this is allowed because 'nat' now appears only at the end of 'npair' and there it
  (a) does not need to consume leading whitespace and
  (b) no longer needs to test for a trailing delimiter

this is allowed because 'pnat' now only remains at the beginning of 'npair'
and there
  (a) does not need to consume leading whitespace and
  (b) is explicitly delimited by 'wel'

the code would still try to print a last element.

also rearrange the loop to avoid code duplication and use delta-1
spaces after the comma.

Removed unused variable 'dict' from act_dict().

Fix pointer signedness problems

See merge request pesco/pdf!5