Default Reader UI

[coolwanglu]

A default reader would be helpful for preliminary users.

The reader UI should be simple, and flexible, it should be able to be easily disabled, probably with a command option. This part may be written in HTML or dynamically generated with JS, it should be integrated with the manifest file seamlessly.

The UI in PDF.js might be a good start/reference.

Example features include next/prev page, zoom and search