Text parser is broken: It assumes it is parsing only a single file.
po4a 0.34 partly fixed this by checking at beginning of each iteration
of the loop if filename changed - but only then - not at the several
places do_paragraph() is done multiple times in same iteration.
This patch makes does the opposite: it ensures that all files contain a
final newline.
This breaks files that has no final newline (but those shouold be rare).
