replace ctor with Memory::begin()

memory.cpp

@@ -17,6 +17,6 @@ public:
 	operator byte() { return 0; }
 } nd;
 
-Memory::Memory() {
+void Memory::begin() {
 	put(nd, 0);
 }

memory.h

@@ -57,7 +57,7 @@ public:
 		return *d;
 	}
 
-        Memory();
+        void begin();
 private:
 	Device *_pages[256];
 };