trunk only: preserving context (include 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

include/hack.h

@@ -88,6 +88,7 @@
 #include "objclass.h"
 #include "youprop.h"
 #include "wintype.h"
+#include "context.h"
 #include "decl.h"
 #include "timeout.h"
 
@@ -100,8 +101,8 @@ NEARDATA extern coord bhitpos;	/* place where throw or zap hits or stops */
 #define FLASHED_LIGHT	3
 #define INVIS_BEAM	4
 
-#define MATCH_WARN_OF_MON(mon)	 (Warn_of_mon && flags.warntype && \
-		   		 (flags.warntype & (mon)->data->mflags2))
+#define MATCH_WARN_OF_MON(mon)	 (Warn_of_mon && context.warntype && \
+		   		 (context.warntype & (mon)->data->mflags2))
 
 #include "trap.h"
 #include "flag.h"