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.

src/client/misc.h

@@ -34,13 +34,9 @@
 #ifndef MISC_H
 #define MISC_H
 
-#include <ctype.h>
 #include <stdio.h>
-#include <sys/types.h>
 #ifdef _WIN32
 #include <windows.h>
-#else
-#include <netinet/in.h>
 #endif
 
 struct ioqueue;