Show menu when paying items

... and have more than 1 billed item, and using non-traditional
menustyle.

I opted to add an extra field to the bill struct, because
that made the code cleaner.

Breaks saves and bones.

include/patchlevel.h

@@ -17,7 +17,7 @@
  * Incrementing EDITLEVEL can be used to force invalidation of old bones
  * and save files.
  */
-#define EDITLEVEL 93
+#define EDITLEVEL 94
 
 /*
  * Development status possibilities.