Merge multiple entries in a better way

[ApsiV11]

Currently the entries are merged for the zip export only after generating the pdf-files. Since Procountor's api only allows one attachment per expense invoice on import, this causes some manual work to be needed to get all the pdfs in. This could be automated:

The problem is that we don't want to lose at least the approval information and maybe not also the date of the expense claim. This info should be in the combined pdf for each of the separate expense claims. The way the info is shown should be designed to use minimal space while also showing the info needed.