Adding assert for type and tag

Implements `assertWrappedElement` to check for correct wrapped element in typified elements.

Closes #53 
We can drastically simplify this method assuming that tag names and attribute values doesn't contain any special symbols that would break regular expressions.

So we do this (in this method):
1. replace `*` with `.*` in the $criteria
2. add `/^(` and `)$` around $criteria
3. do a `preg_match` on it

Then both `CRITERIA_WILDCARD` and `CRITERIA_SEPARATOR` constants can be removed.