Fixes: #158

Resolves the problem of jumping to a wrong possition
that occured while zooming on the last page of the document

Fixes: #166

Fixes #188

Also drop some API version 1 compatibility code.

We have a new ABI and API so the versions should be bumped.

It is now possible to open multiple files by passing them as additional
arguments. The password can now be set with the -w/--password parameter
instead of the argument after the filename.