Pike release bumped to 51 by bump_version.

Rev: src/version.c:1.30

src/version.c

@@ -12,5 +12,5 @@
 void f_version(INT32 args)
 {
   pop_n_elems(args);
-  push_text("Pike v0.5 release 50");
+  push_text("Pike v0.5 release 51");
 }