Update documentation and do some basic housekeeping

src/common/memory.c

@@ -62,19 +62,19 @@ void MEM_Write(mem_block_t *in)
 	WriteBlock(head, in);
 }
 
-int MEM_Read(mem_block_t *out)
+bool MEM_Read(mem_block_t *out)
 {
 	int head;
 
 	head = GetUsedBlock();
 
 	if (head < 0) { // Empty?
-		return -1;
+		return false;
 	}
 
 	ReadBlock(head, out);
 
-	return 0;
+	return true;
 }
 
 void MEM_Free(void)