Restructure asset processor

tools/asset_processor/reader.cpp

@@ -0,0 +1,10 @@
+#include "reader.h"
+#include "util.h"
+#include <string>
+
+std::string opt_param(const std::string& format, int defaultVal, int value) {
+    if (value != defaultVal) {
+        return string_format(format, value);
+    }
+    return "";
+}