sever extracolors from utf8map and ENHANCED_SYMBOLS

move the custom color data into its own field in the glyphmap
and disassociate it from the unicode/utf8 stuff.

move the glyphcache stuff during options processing and parsing
into new file glyphs.c and out of utf8map.c, and make it
general, and not part of ENHANCED_SYMBOLS.

Do the groundwork for allowing glyph color customizations to
work when any symset is loaded and not restrict it only to
the enhanced1 H_UTF8 symsets.

The customizations in effect are still affiliated with a particular
symset.

Also closes #1224, but the PR itself references a data structure
made obsolete by this commit. The curses comment from the PR was
added into the code.

The PR also made several suggestions, but only the first
one has been included in this commit (and no longer based on
the handler), that being:
"allow defining colors if other symbol handling modes are used
(possibly limited to the standard 16 colors)."

FredrIQ also wrote the following suggestions in PR#1224:

Something I was also contemplating, unrelated to implementation of this
support in curses, would be the ability for the following:

allow defining colors if other symbol handling modes are used (possibly limited to the standard 16 colors)
allow defining attributes (for example: glyph:G_pet_female_kitten:U+0066/red/underline)
allow specifying glyphs as wildcards for defining global color/attribute changes

Something I also want to see are keywords for "don't change the current defined data". If this
were to be added, you could for example do this:
OPTIONS=glyph:G_*_fox:U+0064/blue
OPTIONS=glyph:G_statue_*:basechar/gray/underline
for "make all foxes use a blue color, make all statues gray with underline" without needing
to specify the relevant character for every statue. This ("basechar", "basefg", etc)
should perhaps also be added for MENUCOLORS and statushilites, so that you can, for
example, underline all items being worn without needing to specify a bunch of
near-duplicate rules for combining BUC colors + underline worn items
as per #1064

include/wintty.h

@@ -88,20 +88,21 @@ struct WinDesc {
 
 /* descriptor for tty-based displays -- all the per-display data */
 struct DisplayDesc {
-    short rows, cols; /* width and height of tty display */
-    short curx, cury; /* current cursor position on the screen */
-    int color; /* current color */
-    uint32 framecolor; /* current background color */
-    int attrs;         /* attributes in effect */
-    int toplin;        /* flag for topl stuff */
-    int rawprint;      /* number of raw_printed lines since synch */
-    int inmore;        /* non-zero if more() is active */
-    int inread;        /* non-zero if reading a character */
-    int intr;          /* non-zero if inread was interrupted */
-    winid lastwin;     /* last window used for I/O */
-    char dismiss_more; /* extra character accepted at --More-- */
-    int topl_utf8;     /* non-zero if utf8 in str */
-    int mixed;         /* we are processing mixed output */
+    short rows, cols;   /* width and height of tty display */
+    short curx, cury;   /* current cursor position on the screen */
+    uint32 color;        /* current color */
+    uint32 colorflags;   /* NH_BASIC_COLOR or 24-bit color */
+    uint32 framecolor;   /* current background color */
+    int attrs;          /* attributes in effect */
+    int toplin;         /* flag for topl stuff */
+    int rawprint;       /* number of raw_printed lines since synch */
+    int inmore;         /* non-zero if more() is active */
+    int inread;         /* non-zero if reading a character */
+    int intr;           /* non-zero if inread was interrupted */
+    winid lastwin;      /* last window used for I/O */
+    char dismiss_more;  /* extra character accepted at --More-- */
+    int topl_utf8;      /* non-zero if utf8 in str */
+    int mixed;          /* we are processing mixed output */
 };
 
 #endif /* WINDOW_STRUCTS */
@@ -188,10 +189,9 @@ extern void term_end_raw_bold(void);
 extern void term_end_color(void);
 extern void term_start_color(int color);
 extern void term_start_bgcolor(int color);
-#ifdef ENHANCED_SYMBOLS
-extern void term_start_24bitcolor(struct unicode_representation *);
-extern void term_end_24bitcolor(void); /* termcap.c, consoletty.c */
-#endif
+extern void term_start_extracolor(uint32 nhcolor);
+extern void term_end_extracolor(void); /* termcap.c, consoletty.c */
+extern void term_start_256color(int idx);
 
 /* ### topl.c ### */