more robust asx parser for wrong case and test

I made the comparisons for 'REF' and 'HREF', in the ASX parser, a little more robust to accommodate cases when they are typed in different case letters. 
e.g. 'Ref' and 'href' respectively.
I also added a test case for that.

Your parser helped me a lot, and this feature some more.

Hope you like it!

Thanks!

Chris