CHANGE_COLOR palette option adjustments

It was too early to call the windowport change_color() routine
while processing the config file. The windowport was not yet
fully operational.

Now the palette option processing will just place the rgb
value into the appropriate ga.altpalette[CLR_MAX] entry.

init_sound_disp_gamewindows(void) [allmain.c] calls
change_palette() [coloratt.c] and it will call the windowport
change_color() function for each ga.altpalette[] entry that
has been set.

Notes:
The rgb values stored in ga.altpalette[] have the NH_ALTPALETTE bit set
so that the rgb value of 0 can be stored and be distinguishable from
a "not set" entry.

The NH_ALTPALETTE bit is cleared from the rgb value in change_palette()
prior to calling the windowport change_color() function.

The syntax for palette is colorname/r-g-b.
For example: palette:black/12-12-12

colorname must be one of the NH_BASIC_COLOR names or a suitable
alias for one of those 16 entries.

Some of the windowport CHANGE_COLOR functions had the wrong parameters,
perhaps due to bitrot. Those have been corrected to match the prototype.

src/coloratt.c

@@ -1016,4 +1016,80 @@ get_nhcolor_from_256_index(int idx)
         retcolor = color_256_definitions[idx].value;
     return retcolor;
 }
+
+#ifdef CHANGE_COLOR
+
+int
+count_alt_palette(void)
+{
+    int clr, clrcount = 0;
+
+    for (clr = 0; clr < CLR_MAX; ++clr) {
+        if (ga.altpalette[clr] != 0U)
+            clrcount++;
+    }
+    return clrcount;
+}
+
+int
+alternative_palette(char *op)
+{
+    char buf[BUFSZ], *c_colorid, *c_colorval, *cp;
+    int reslt = 0, coloridx = CLR_MAX;
+    long rgb = 0L;
+    boolean slash = FALSE;
+
+    if (!op)
+        return 0;
+
+    Snprintf(buf, sizeof buf, "%s", op);
+    c_colorval = (char *) 0;
+    c_colorid = cp = buf;
+    while (*cp) {
+        if (*cp == ':' || *cp == '/') {
+            if (*cp == '/') {
+                slash = TRUE;
+                *cp = '\0';
+            }
+        }
+        cp++;
+        if (slash) {
+            c_colorval = cp;
+            slash = FALSE;
+        }
+    }
+    /* some sanity checks */
+    if (c_colorid && *c_colorid == ' ')
+        c_colorid++;
+    if (c_colorval && *c_colorval == ' ')
+        c_colorval++;
+    if (c_colorid)
+        coloridx = match_str2clr(c_colorid, TRUE);
+
+    if (c_colorval && coloridx >= 0 && coloridx < CLR_MAX) {
+        rgb = rgbstr_to_int32(c_colorval);
+        if (rgb != -1) {
+            ga.altpalette[coloridx] = (uint32) rgb | NH_ALTPALETTE;
+            /* use COLORVAL(ga.altpalette[coloridx]) to get
+               the actual rgb value out of ga.altpalette[] */
+            reslt = 1;
+        }
+    }
+    return reslt;
+}
+
+void
+change_palette(void)
+{
+    int clridx;
+
+    for (clridx = 0; clridx < CLR_MAX; ++clridx) {
+        if (ga.altpalette[clridx] != 0) {
+            long rgb = (long) (ga.altpalette[clridx] & ~NH_ALTPALETTE);
+            (*windowprocs.win_change_color)(clridx, rgb, 0);
+        }
+    }
+}
+#endif /* CHANGE_COLOR */
+
 /*coloratt.c*/