- Make the autosegs read-only.

- Derive PClass from dobject.cpp. This has one major ramification: Since the PClass
  is not allocated until runtime, you cannot initialize any static/global data
  structures with pointers to PClasses using RUNTIME_CLASS. Attempting to do so
  will just initialize with a NULL pointer. Instead, you can initialize using
  the address of the pointer returned by RUNTIME_CLASS and dereference that. By
  the time you have an opportunity to dereference it, it will no longer be NULL.
- Sync CmakeLists.txt.
- Random fixes for problems GCC spotted.

SVN r1852 (scripting)

src/zscript/vmexec.h

@@ -540,7 +540,7 @@ begin:
 		}
 		if (B & REGT_FINAL)
 		{
-			return MIN(numret, a + 1);
+			return a < numret ? a + 1 : numret;
 		}
 		NEXTOP;
 	OP(RESULT):