Add GUI to use search API

[rvanlaak]

In #231 an API has been introduced to search in the result html. When this API works, the next step could be to add an GUI that makes use of this API.

The GUI should contain form elements to feed the search-API with data. A first version could have two tabs, one for search and one for search & replace. Both tabs can contain radio buttons for the search method (regular vs. regex) and search direction (up vs. down)

[coolwanglu]

https://github.com/coolwanglu/pdf2htmlEX/wiki/Unfeatures#ui

UI is never a focus of pdf2htmlEX, publisher are meant to provide their UI with pdf2htmlEX.js as a reference.

I'm closing this one as a duplicate of #219

[BockwurstJoe]

I am looking for a reader/viewer application as descibed here: #219 has there been any effort since the issue was closed? I was trying really hard to implement one by myself but I am struggling with displaying it right on many devices.