trunk only: preserving context (src files)

Pat Rankin wrote:
> collect them all into some new struct and
> save that separately rather than jamming more non-option stuff
> into struct flags.

This patch:
- collects all context/tracking related fields from flags
  into a new structure called "context."
It also adds the following to the new structure:
- stethoscope turn support
- victual support
- tin support

src/rumors.c

@@ -355,7 +355,7 @@ register struct monst *oracl;
 #else
         money2mon(oracl, (long)u_pay);
 #endif
-	flags.botl = 1;
+	context.botl = 1;
 	add_xpts = 0;	/* first oracle of each type gives experience points */
 	if (u_pay == minor_cost) {
 		outrumor(1, BY_ORACLE);