Add support for documents with unequal page sizes
When viewing documents with pages of differing sizes, zathura uses the largest page size as the size for all pages. In the case of e.g. papers from JSTOR (and other kinds of documents), the first page is much larger. This means that zathura adds massive padding around most pages, jumping to a page jumps into its surrounding whitespace, and the reading experience is in general very janky.
Here is a PDF affected by this problem: https://vladh.net/t/tok.pdf
This issue makes zathura quite unusable for me, since I'm experiencing this issue with quite a few documents, and it makes reading very unpleasant. Would this be a difficult thing to fix? I am happy to contribute if given some pointers as to the relevant code etc.