Fixed problem where, when defining more than one attribute, the attribute value of the first hangs around to the seond attribtue. This was fixed before, but because of some problem with a little bit of duoplicate code, it happend again. And all syntax errors are now signaled by throwing an exception, instead of cout. This is because it is quite usefull to generate files using cout, but this is hard if all your errors then show up in that file.