cddump() takes a daddr_t parameter. Call that parameter 'blkno' and not
'secno'. This is what sddump() already does and consistant is good.
No function change.
For some mdoc(7) macros, it is (unfortunately) semantically significant
whether they are the first macro on the line or called by another macro.
To help debugging, indicate this property "first macro on a new input line"
by prefixing an asterisk to the line number in -Ttree output.
Block closing macros do not allocate a new node but finish an existing
one, so they miss the clearing of MDOC_NEWLINE in mdoc.c, node_alloc().
Consequently, MDOC_NEWLINE must be cleared before processing the next
macro on the same line.
This fixes horizontal spacing for input lines beginning like .Oc Ns ...

Issue found by Franco Fichtner <franco at lastsummer dot de>
while working on DragonFly mandoc integration.
Use normal line macro recognition, do not attempt to roll your own.
This fixes horizontal spacing when an Ns macro follows a block-closing
macro and the corresponding block-opening macro is not on the same line.
Macros following block closing macros aren't line macros.
Testing mdoc_macro.c 1.79 and mdoc_man.c 1.51.

Thanks to Franco Fichtner <franco at lastsummer dot de>
for providing the test case this patch was based on.
Some missing .Pa macros in FILES sections;
from Jan Stary <hans at stare dot cz>;
discussed with jmc@.