https://github.com/coolwanglu/pdf2htmlEX/issues/180

Add key handler, and implement page up, page down, ctrl-home and ctrl-end.

First commit on github and first javascript coding :)
https://github.com/coolwanglu/pdf2htmlEX/issues/180

Better name for the key handler.
https://github.com/coolwanglu/pdf2htmlEX/issues/180

Call e.preventDefault() when the key was handled.
https://github.com/coolwanglu/pdf2htmlEX/issues/180

Scroll pages with alt-page up/down, not page up/down.

Implement screen scrolling for page up/down.

Fix comment about which key is up (code was right, but comments were inverted :D)
Use return in the non-handled key cases, and call preventDefault() in a single place, as suggested.

https://github.com/coolwanglu/pdf2htmlEX/issues/180
Simplify the implementation of ctrl-home, we don't need to care about pages in this case.

https://github.com/coolwanglu/pdf2htmlEX/issues/180
Added myself in AUTHORS, as requested
Use scrollHeight to find out how to scroll to the end for ctrl-end.

https://github.com/coolwanglu/pdf2htmlEX/issues/180
add navigation key handler
fix