Enhancements - T2::legacyParse

- T2 can now parse all supported legacy formats (ff2, ff3) as well as
  ff4.
- Added tag and attribute support to T2.
- Added T2 unit tests for all formats.

src/Context.cpp

@@ -377,6 +377,10 @@ std::cout << "# parse tag removal '" << *arg << "'" << std::endl;
         if (foundSequence)
           foundSomethingAfterSequence = true;
 
+        if (arg->find (',') != std::string::npos)
+          throw stringtable.get (TAGS_NO_COMMA,
+                                 "Tags are not permitted to contain commas.");
+
         tagRemovals.push_back (arg->substr (1, std::string::npos));
       }