Add support for ncurses A_ITALICS style as an alternative to A_UNDERLINE
Ncurses Frotz uses A_UNDERLINE to print text in EMPHASIS_STYLE. This is consistent with how some - perhaps most? - of Infocom's interpreters did it. I know from my own experience that their Macintosh interpreter used underlined text (probably for readability, since from what I remember italics didn't look that great with the font they used), and I've seen from screenshots that their Amiga interpreter did as well.
However, at the very least their Atari ST interpreter used italics, as can be seen in this screenshot from Bureaucracy: https://www.mobygames.com/game/atari-st/bureaucracy/screenshots/gameShotId,38020/
In fact, Trinity has a bunch of special cases for Atari ST to take advantage of this. See https://github.com/the-infocom-files/trinity/issues/5 for a brief overview.
According to https://invisible-island.net/ncurses/NEWS.html#index-t20130831 ncurses added an A_ITALIC style for italics in 2013. I've tested it, and it worked for me.
Perhaps there should be an option to select if Frotz should use A_UNDERLINE or A_ITALIC when A_ITALIC is available? I would be sad to see A_UNDERLINE removed completely, because that's how I remember the games looking back in the day. (And I guess A_ITALIC is a non-standard extension as far as curses go?) But I've seen Inform games - the names escape me at the moment - that looked like they assume the text will be printed as italics, not underline, so an option would be nice...