feat: support alternative vcm models syntax

test/coders/xml.cpp

@@ -0,0 +1,24 @@
+#include <gtest/gtest.h>
+
+#include "coders/xml.hpp"
+#include "coders/commons.hpp"
+
+TEST(XML, VCM) {
+    std::string code = ""
+        "@line x1 y1 z1\n"
+        "# @tst ysfdrg\n"
+        "@box {\n"
+        "  @rect texture \"$2\"\n"
+        "  @utro a 53.1\n"
+        "}\n"
+    ;
+    std::cout << code << std::endl;
+
+    try {
+        auto document = xml::parse_vcm("<test>", code, "test");
+        std::cout << xml::stringify(*document);
+    } catch (const parsing_error& err) {
+        std::cerr << err.errorLog() << std::endl;
+        throw err;
+    }
+}