Fixes url whitespaces in epub documents
Summary:
libepub can't handle whitespace url encodings. This is why epub documents containing whitespaces urls aren't
displayed correctly. Since libepub doesn't seem to be maintained anymore, it might be better to fix this issue here.
BUG: 334711
Test Plan: Example epubs are in the ticket.
Reviewers: Okular, aacid
Reviewed By: Okular, aacid
Subscribers: ngraham, aacid, okular-devel
Tags: Okular
Differential Revision: https://phabricator.kde.org/D14310