WIP: Added a few ugly testcases

[JensHeinrich]

Only added tests right now

includes #74

[JensHeinrich]

The problem seems to be the interweaving in the AST;
technically there are two AST here I think:

• the XML/HTML one
• the jinja one

[JensHeinrich]

So I just had an weird idea:
Maybe a structure representing an construct yielding an opening tag and a structure yielding a closing tag could be created to accomodate the content of the those conditional blocks
then the optional block could use a list of tuples of condition and opening tag and a list of tuples of condition and closing tag to define this
having these lists a closing tag like in test_different_container_openings(self) could probably be implemented too