another update to the soundlib interface

sound_verbal(char *text, int32_t gender, int32_t tone, int32_t vol,
             int32_t moreinfo);
    -- NetHack will call this function when it wants to pass text of
       spoken language by a character or creature within the game.
    -- text is a transcript of what has been spoken.
    -- gender indicates MALE or FEMALE sounding voice.
    -- tone indicates the tone of the voice.
    -- vol is the volume (1% - 100%) for the sound.
    -- moreinfo is used to provide additional information to the soundlib.
    -- there may be some accessibility uses for this function.

It may be useful for accessibility purposes too.

A preliminary implementation has been attempted for macsound to test
the interface on macOS. No tinkering of the voices has been done.

Use of the test implementation requires the following at build time with make.
    WANT_SPEECH=1
That needs to be included on the make command line to enable the test code,
otherwise just the interface update is compiled in.

I don't know for certain when AVSpeechSynthesizer went into macOS, but older versions
likely don't support it, and would just leave off the WANT_SPEECH=1.

If built with WANT_SPEECH=1, the 'voices' NetHack option needs to be enabled.

It was a bit strange, when I first started up the test, to hear Asidonhopo,
the shopkeeper, talking to me as I entered his shop and interacted with him.

doc/sound.txt

@@ -90,6 +90,9 @@ There are 4 distinct types of sound sound_triggers used by NetHack.
                                  (ambience_upate), likely with a different
                                  hero proximity value.
 
+    SOUND_TRIGGER_VERBAL         Invoked by the core when someone (or something)
+                                 is speaking.
+
 
 The types of sound sound_triggers supported by a particular soundlib
 implementation are specified in that library's soundlib file, which is usually
@@ -109,17 +112,20 @@ the sound_triggers field of the sound_procs struct:
         void (*sound_play_usersound)(char *filename, int32_t volume,
               int32_t usidx);
         void (*sound_ambience)(int32_t ambienceid, int32_t ambience_action,
-               int32_t hero_proximity);
+              int32_t hero_proximity);
+        void (*sound_verbal)(char *text, int32_t gender, int32_t tone,
+              int32_t vol, int32_t moreinfo);
     };
 
-A sound library integration support file can implement one, two, three or
-four of the sound trigger types. The more types of sound_triggers the
+A sound library integration support file can implement one, two, three, four,
+five, or six of the sound trigger types. The more types of sound_triggers the
 soundlib implements, the more full-featured the sound experience will be
 during the game.
 
 The values can be or'd together in the sound_triggers field initialization.
     SOUND_TRIGGER_USERSOUNDS | SOUND_TRIGGER_HEROMUSIC
         | SOUND_TRIGGER_ACHIEVEMENTS | SOUND_TRIGGER_SOUNDEFFECTS
+        | SOUND_TRIGGER_AMBIENCE | SOUND_TRIGGER_VERBAL
 
 
 II.  Interface Specification
@@ -248,6 +254,18 @@ sound_ambience(int32_t ambienceid, int32_t ambience_action,
        If the distance of the hero from the source of the ambience does
        matter, then a distance value will be in hero_proximity.
 
+sound_verbal(char *text, int32_t gender, int32_t tone, int32_t vol,
+             int32_t moreinfo);
+    -- NetHack will call this function when it wants to pass text of
+       spoken language by a character or creature within the game.
+    -- text is a transcript of what has been spoken.
+    -- gender indicates MALE or FEMALE or NEUTRAL (either MALE
+       or FEMALE) voice.
+    -- tone indicates the tone of the voice.
+    -- vol is the volume (1% - 100%) for the sound.
+    -- moreinfo is used to provide additional information to the soundlib.
+    -- there may be some accessibility uses for this function.
+
 
 III.  Global variables
 
@@ -264,6 +282,11 @@ gc.chosen_soundlib
 ga.active_soundlib
 a usersound mappings reference
 
+iflags.sounds is the master on/off swith to control whether any audio
+is produced by the soundlib interface
+
+iflags.voice is the master on/off switch for voices produced by
+the soundlib interface.
 
 IV.   Other related routines
 
@@ -360,14 +383,15 @@ use the following guidelines:
            SOUNDID(myprefix),
            SOUND_TRIGGER_USERSOUNDS | SOUND_TRIGGER_HEROMUSIC
               | SOUND_TRIGGER_ACHIEVEMENTS |SOUND_TRIGGER_SOUNDEFFECTS
-              | SOUND_TRIGGER_AMBIENCE,
+              | SOUND_TRIGGER_AMBIENCE | SOUND_TRIGGER_VERBAL,
            myprefix_init_nhsound,
            myprefix_exit_nhsound,
            myprefix_achievement,
            myprefix_soundeffect,
            myprefix_hero_playnotes,
            myprefix_play_usersound,
-           myprefix_ambience),
+           myprefix_ambience,
+           myprefix_verbal),
        };
 
    The first entry in this structure should be the SOUNDID(myprefix)
@@ -526,6 +550,8 @@ static void sample_hero_playnotes(int32_t, const char *, int32_t);
 static void sample_play_usersound(char *, int32_t, int32_t);
 static void sample_ambience(int32_t ambienceid, int32_t ambience_action,
                             int32_t hero_proximity);
+static void (*sound_verbal)(char *text, int32_t gender, int32_t tone,
+              int32_t vol, int32_t moreinfo);
 
 struct sound_procs sample_procs = {
     SOUNDID(sample),
@@ -539,6 +565,7 @@ struct sound_procs sample_procs = {
     sample_hero_playnotes,
     sample_play_usersound,
     sample_ambience,
+    sample_verbal
 };
 
 static void
@@ -588,5 +615,11 @@ sample_ambience(int32_t ambienceid, int32_t ambience_action,
 {
 }
 
+static void
+sample_verbal(char *text, int32_t gender, int32_t tone,
+              int32_t vol, int32_t moreinfo)
+{
+}
+
 /* end of sample.c */
 -- >8 --