attribute check timer (trunk only)

Move the counter for the next attribute check to the context
structure.

This increments patchlevel so previous save and bones
files are unuseable after applying.

include/context.h

@@ -75,6 +75,7 @@ struct context_info {
 	unsigned startingpet_mid;
 	int	 warnlevel;
 	int	 djinni_count, ghost_count;	/* potion effect tuning */
+	long next_attrib_check;	/* next attribute check */
 	long stethoscope_move;
 	short stethoscope_movement;
 	boolean  travel;	/* find way automatically to u.tx,u.ty */