srogue: add arrow-key support.

This is a first attempt which may not be completely portable.

srogue/io.c

@@ -20,6 +20,8 @@
 #include "rogue.h"
 #include "rogue.ext"
 
+int md_readchar(WINDOW *win);
+
 /*
  * msg:
  *	Display a message at the top of the screen.
@@ -132,7 +134,7 @@ readchar()
 	char c;
 
 	fflush(stdout);
-        return( wgetch(cw) );
+        return( md_readchar(cw) );
 }
 
 char *hungstr[] = {