fix #H2694 - egg hatching feedback

A bug report from ten and half years ago...
If a carried egg hatches, the message is
|<foo> drops from your pack.
and if tame, is followed by
|Its cries sound like {mommy,daddy}.
The latter was issued even when <foo> has no speech capability.

Replace "its cries sound like" with "its <vocalize>ing sounds like"
for suitable value of <vocalize>.

This adds two new monster sounds, MS_BELLOW and MS_CHIRP, also two
new sound effect codes, se_chirp and se_croc_bellow.

We had MS_SILENT for crocodile.  On wikipedia, crocodile is described
as the most vocal reptile.  Adult males make a load bellowing noise
and hatchlings make a chirping noise.

This changes crocodile, titanothere, and baluchitherium from MS_SILENT
to MS_BELLOW and baby crocodile from MS_SILENT to MS_CHIRP.  Chirp
might be appropriate for lizards and lizard-like amphibians but I've
left those as MS_SILENT.

[Noticed but not changed:  lizards and lizard-like amphibians aren't
flagged as oviparous.  Shouldn't they be?]

src/timeout.c

@@ -1012,8 +1012,10 @@ hatch_egg(anything *arg, long timeout)
                 You_see("%s %s out of your pack!", monnambuf,
                         locomotion(mon->data, "drop"));
             if (yours) {
-                pline("%s cries sound like \"%s%s\"",
+                pline("%s %s %s like \"%s%s\"",
                       siblings ? "Their" : "Its",
+                      ing_suffix(cry_sound(mon)),
+                      (is_silent(mon->data) || Deaf) ? "seems" : "sounds",
                       flags.female ? "mommy" : "daddy", egg->spe ? "." : "?");
             } else if (mon->data->mlet == S_DRAGON && !Deaf) {
                 SetVoice(mon, 0, 80, 0);