change redisplay to handle some cases where the line consumes more than the number of physical screen lines; add regerror() error messages if regular expression compilation fails; make sure active region readline variables are displayed with bind -v; partial fix for bind -x and commands containing quoting characters

include/shmbchar.h

@@ -71,6 +71,21 @@ is_basic (char c)
          & 1;
 }
 
+#if 0
+/* XXX - FUTURE */
+/* All locale encodings (see localcharset.h) map the characters 0x00..0x7F
+   to U+0000..U+007F, like ASCII, except for
+     CP864      different mapping of '%'
+     SHIFT_JIS  different mappings of 0x5C, 0x7E
+     JOHAB      different mapping of 0x5C
+   However, these characters in the range 0x20..0x7E are in the ISO C
+   "basic character set" and in the POSIX "portable character set", which
+   ISO C and POSIX guarantee to be single-byte.  Thus, locales with these
+   encodings are not POSIX compliant.  And they are most likely not in use
+   any more (as of 2023).  */
+#define is_basic(c) ((unsigned char) (c) < 0x80)
+#endif
+
 #else
 
 static inline int