Remove the MD5-based manifest file system.

A long time ago, it seemed like a good idea to arrange that binaries
of my puzzles would automatically cease to identify themselves as a
particular upstream version number if any changes were made to the
source code, so that if someone made a local tweak and distributed the
result then I wouldn't get blamed for the results. Since then I've
decided the whole idea is more trouble than it's worth, so I'm
retiring it completely.

[originally from svn r10264]

version.c

@@ -2,31 +2,6 @@
  * Puzzles version numbering.
  */
 
-#define STR1(x) #x
-#define STR(x) STR1(x)
+#include "version.h"
 
-#ifdef INCLUDE_EMPTY_H
-/*
- * Horrible hack to force version.o to be rebuilt unconditionally in
- * the automake world: empty.h is an empty header file, created by the
- * makefile and forcibly updated every time make is run. Including it
- * here causes automake to track it as a dependency, which will cause
- * version.o to be rebuilt too.
- *
- * The space between # and include causes mkfiles.pl's dependency
- * scanner (for all other makefile types) to ignore this include,
- * which is correct because only the automake makefile passes
- * -DINCLUDE_EMPTY_H to enable it.
- */
-# include "empty.h"
-#endif
-
-#if defined VER
-
-char ver[] = "Version: " STR(VER);
-
-#else
-
-char ver[] = "Unidentified build, " __DATE__ " " __TIME__;
-
-#endif
+char ver[] = VER;