Various fixes to vm_interpreted.c:

- Add opStack protection
- Fix dataMask check for OP_BLOCK_COPY
- Add instruction number check for conditional jumps
- Make errors in VM_PrepareInterpreter nonfatal

code/qcommon/vm_local.h

@@ -190,3 +190,5 @@ vmSymbol_t *VM_ValueToFunctionSymbol( vm_t *vm, int value );
 int VM_SymbolToValue( vm_t *vm, const char *symbol );
 const char *VM_ValueToSymbol( vm_t *vm, int value );
 void VM_LogSyscalls( int *args );
+
+void VM_BlockCopy(unsigned int dest, unsigned int src, size_t n);