Support for local PDF documents

[cboddy]

Hello!

Firstly congrats on a superb App, I found it last night and am enjoying it very much.

Before starting work on a pull request I'd like to seek your opinion regarding PDF support.

I'd like to suggest adding support for PDF docs (in addition to epub) using iText or similar for PDF-text extraction with some minimal filtering to remove noisy lines (like mathematical equations in scholarly articles).

Thoughts?
Chris

[mattiasaxell]

@cboddy I agree with you a lot!

PDF Support would be cool! Also looking forward to hear thoughts. 😄