Break inclusion cycle: prototypes.h and commands.h included each

other.  Ensure headers in include/ can be included in any order
(except for econfig-spec.h, which is special).  New header types.h to
help avoid inclusion cycles.  Sort include directives.  Remove some
superflous includes.

include/budg.h

@@ -34,6 +34,9 @@
 #ifndef BUDG_H
 #define BUDG_H
 
+#include "types.h"
+#include "item.h"
+
 #define SCT_EFFIC (SCT_TYPE_MAX + 1)
 
 void fill_update_array(int *bp, struct sctstr *sp);