Text tools (select, find)

[HemulGM]

No description provided.

[omonien]

Can you explain a bit more what your changes are about? I will still be on the road for the next several days, so I have limited time to check the code in full.

[HemulGM]

Add new functions from dll

Added methods for working with text for the "page". Including with FPDF_TEXTPAGE

Added a new class that represents the search query. You can destroy it whenever you want, and destroying the page won't lead to an error either.

Added a scrollbar for scrolling pages in the view control. And I added an example of performing a search to the example. + added a test method for highlighting what was found.

[omonien]

Thanks @HemulGM - solid implementation! Clean interface-based design with IPageSearch and proper lifecycle management via FSearchNotifies. The CurrentPage visibility change is a welcome improvement. Merging this now.