Added decl_early_init() which is called when PLAYAGAIN is supported.

decl_early_init() is called when we are starting a game.  On first
start, it validates that global state is in the expected state.
When called on subsequent starts, it initializes global state to
expected state.

include/config.h

@@ -552,10 +552,13 @@ typedef unsigned char uchar;
 
 #endif
 
-/* PLAYAGAIN is support for allowing the game shell to stay open after the player
-   saves or dies.  This requires that the game engine can be re-entered to start
-   another game.  This support is primarily about ensuring that game engine
-   state is cleaned up properly to allow the game engine to be re-initialized. */
+/* PLAYAGAIN support for allowing the game shell to stay open after the player
+ * saves or dies.  This requires that the game engine can be re-entered to
+ * start another game.
+ *
+ * This support does not include supporting playing another game when
+ * a panic has occured due to undetermined state the engine is left in after a
+ * panic */
 /* #define PLAYAGAIN */
 
 /* End of Section 4 */

include/extern.h

@@ -251,6 +251,9 @@ E void FDECL(destroy_drawbridge, (int, int));
 /* ### decl.c ### */
 
 E void NDECL(decl_init);
+#ifdef PLAYAGAIN
+E void NDECL(decl_early_init);
+#endif
 
 /* ### detect.c ### */