…title.

… prefixes, in its representation of instance elements (such as orx:meta). It removes the prefixes from the element names. This makes it impossible to match the element names with names that do include a prefix. Here is one possible solution:

 Capture the namespace names and prefixes from the html element, and make them available later when searching for instance elements by name. See the doc comments in TreeElementNameComparator for details.

Instead of having namespace URI -> namespace prefix map,
the prefix is kept as TreeElement's field the same way as the namespace
URI is.

Changes:
- removed debug logging
- simplified if conditions since own block for each
  condition is no longer needed as there is no debug logging
- removed `namespace` final variable and the related
  null check