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/fountain.c

@@ -211,7 +211,7 @@ drinkfountain()
 		for (ii = 0; ii < A_MAX; ii++)
 		    if (ABASE(ii) < AMAX(ii)) {
 			ABASE(ii) = AMAX(ii);
-			flags.botl = 1;
+			context.botl = 1;
 		    }
 		/* gain ability, blessed if "natural" luck is high */
 		i = rn2(A_MAX);		/* start at a random attribute */