Use dark gray color for black glyphs in TTY

This is Michael Deutschmann's use_darkgray -patch.
Adds a boolean option use_darkgray, settable in config file.

This patch has been in use on NAO for years, and I have heard
once someone say their terminal didn't support the dark gray
color.

include/flag.h

@@ -295,6 +295,7 @@ struct instance_flags {
 	boolean wc2_softkeyboard;	/* use software keyboard */
 	boolean wc2_wraptext;		/* wrap text */
 	boolean wc2_selectsaved;	/* display a menu of user's saved games */
+	boolean wc2_darkgray;		/* try to use dark-gray color for black glyphs */
 	boolean  cmdassist;	/* provide detailed assistance for some commands */
 	boolean	 clicklook;	/* allow right-clicking for look */
 	boolean	 obsolete;	/* obsolete options can point at this, it isn't used */

include/winprocs.h

@@ -219,7 +219,8 @@ NEARDATA struct window_procs windowprocs;
 #define WC2_WRAPTEXT		0x04L	/* 03 wrap long lines of text                */
 #define WC2_HILITE_STATUS	0x08L	/* 04 hilite fields in status                */ 
 #define WC2_SELECTSAVED		0x10L	/* 05 saved game selection menu              */
-					/* 27 free bits */
+#define WC2_DARKGRAY		0x20L	/* 06 use bold black for black glyphs        */
+					/* 26 free bits */
 
 #define ALIGN_LEFT	1
 #define ALIGN_RIGHT	2