Example wizard: Add search field

[tkutz]

For better usability, a search field should be provided which allows to search over the provided html files.

The tree section should filter its content for elements containing a searched term. The details section should highlight the searched term.

[tkutz]

First prototype using Lucene implemented on branch https://github.com/Yakindu/statecharts/tree/feature_example_search

[tkutz]

It is not yet production ready. For highlighting search terms in details section, a copy of the html with different css styling is created, which is only a workaround here. It would be better to do it in-memory. Also, some usability testing is required.