script: move CScriptID to standard.h and add a ctor for creating them from CScripts

This allows for a reversal of the current behavior.

This:
CScript foo;
CScriptID bar(foo.GetID());

Becomes:
CScript foo;
CScriptID bar(foo);

This way, CScript is no longer dependent on CScriptID or Hash();

src/crypter.cpp

@@ -5,6 +5,7 @@
 #include "crypter.h"
 
 #include "script/script.h"
+#include "script/standard.h"
 #include "util.h"
 
 #include <string>