Small fix in script to create test documents

Apparently, Github pages does not support symlinks.
Therefore, replace symlinks with copies.
Mock welcome dialog (wip)

Create a mock welcome dialog. This is still pretty much work in progress
and will be cleaned up in the next few commits.
TODO:
* Polish images
* clean up JavaScript
* implement acceptstep2 button
* URL to k2pdfopt
Cleanup preferences

* Rename preference "k2pdfoptpath" to "k2pdfoptPath" to
  be consistent with k2pdfoptPlatform.
* Cleanup default preferences file.
Finish welcome dialog.

* Add model picker that is outsourced so it can be reused in
  the options dialog.
* Add Email setup step with an option to send a test document.
* Add some usage instructions once everything is set up.
Implement options dialog

All except the "margins" tab are implemented.
Update README.md and install script