Refactor INO to CPP converter

tests/ino2cpp/multifiles/bar.ino

@@ -0,0 +1,3 @@
+void barFunc () { // my comment
+
+}

tests/ino2cpp/multifiles/foo.pde

@@ -0,0 +1,13 @@
+
+void setup() {
+    barFunc();
+    fooFunc();
+}
+
+void loop() {
+
+}
+
+char* fooFunc() {
+
+}