trunk only: preserving context (sys 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

sys/amiga/Makefile.agc

@@ -1267,10 +1267,10 @@ $(I)global.h:  $(I)coord.h $(I)pcconf.h $(I)amiconf.h
 	-setdate $(I)global.h
 	-c:wait 2
 
-$(I)hack.h:  $(I)config.h $(I)trap.h $(I)decl.h $(I)dungeon.h $(I)monsym.h \
-		$(I)mkroom.h $(I)objclass.h $(I)flag.h $(I)rm.h $(I)vision.h \
-		$(I)display.h $(I)wintype.h $(I)engrave.h $(I)rect.h \
-		$(I)region.h $(I)trampoli.h
+$(I)hack.h:  $(I)config.h $(I)context.h $(I)trap.h $(I)decl.h $(I)dungeon.h 
+		$(I)monsym.h $(I)mkroom.h $(I)objclass.h $(I)flag.h $(I)rm.h 
+		$(I)vision.h $(I)display.h $(I)wintype.h $(I)engrave.h 
+		$(I)rect.h $(I)region.h $(I)trampoli.h
 	-setdate $(I)hack.h
 	-c:wait 2
 

sys/amiga/Makefile.ami

@@ -1607,10 +1607,10 @@ $(I)global.h:  $(I)coord.h $(I)pcconf.h $(I)amiconf.h
 	-setdate $(I)global.h
 	-wait 2
 
-$(I)hack.h:  $(I)config.h $(I)trap.h $(I)decl.h $(I)dungeon.h $(I)monsym.h \
-		$(I)mkroom.h $(I)objclass.h $(I)flag.h $(I)rm.h $(I)vision.h \
-		$(I)display.h $(I)wintype.h $(I)engrave.h $(I)rect.h \
-		$(I)region.h $(I)trampoli.h
+$(I)hack.h:  $(I)config.h $(I)context.h $(I)trap.h $(I)decl.h $(I)dungeon.h 
+		$(I)monsym.h $(I)mkroom.h $(I)objclass.h $(I)flag.h $(I)rm.h
+		$(I)vision.h $(I)display.h $(I)wintype.h $(I)engrave.h 
+		$(I)rect.h $(I)region.h $(I)trampoli.h
 	-setdate $(I)hack.h
 	-wait 2