Fix problem introduced in
b1ecd9b6 (August 8, 2019)

When sbbs_t::printfile() is used to display a file that is < 2MB in size
and the P_OPENCLOSE mode flag was not specified, the file is read and
displayed one line at a time. This allows for the quick display of very
large files. This was accomlished by calling sbbs_t::putmsg() for each
line. Unfortunately, putmsg() would save and restore console mode flags
like the auto-screen pause control flags stored in sbbs_t::sys_misc
so this would render some features like the POFF @-code, inoperable.
This problem was reported by WitNik with files displayed from
Bulleeye! Bulletins.

Other issues were discovered with the WORDWRAP/WRAPOFF @-codes.

Fixed with the addition of sbbs_t::putmsgfrag() which is used by
printfile() to display a message fragment (one line) without
saving/restoring console state flags.