added function test with gcd calculation

code/gcd.txt

@@ -0,0 +1,39 @@
+>main
+gto
+:gcd
+=v
+=u
+$u
+$v
+>loop
+gge
+$u
+=t
+$v
+=u
+$t
+=v
+:loop
+$v
+0
+>ret
+gle
+$v
+=t
+$u
+$v
+mod
+=v
+$t
+=u
+>loop
+gto
+:ret
+$u
+ret
+:main
+4
+16
+>gcd
+fun
+end

main.cpp

@@ -68,7 +68,7 @@ int main(int argc, const char * argv[]) {
 
         bool done {false};
         std::string base_url {"https://www.swiftcoder.nl/cpp1/"};
-        std::string next_url {"start.txt"};
+        std::string next_url {"gcd.txt"};
         std::string code;
         requester req;
         interpreter proc;
@@ -77,7 +77,7 @@ int main(int argc, const char * argv[]) {
             // std::cerr << code << '\n';
             std::istringstream in {code};
             next_url = proc.eval(in, done);
-            std::cerr << next_url << '\n';
+            SCInfo(logger, next_url);
         }
         std::cout << next_url << '\n';