Adding support for split zip files

[Daniel451]

Large datasets (roughly >3GB) cannot be uploaded at once so that one has to split large datasets manually into either smaller datasets or multiple zip files (by hand or custom scripts). It clearly discourages uploading large datasets.

This is against the intended use-case of the ImageTagger: rendering the usage of large datasets + annotations easy to handle.

One could easily automatically split zip files by using 7zip, for example:

7z a -tzip dataset.zip -v1G *.png

This way, arbitrarily large datasets will get packed into split zip files, each of a size of exactly 1GB of data.

Unfortunately, the ImageTagger rejects files of extension:

dataset.zip.001
dataset.zip.002
dataset.zip....
dataset.zip.N

Accepting such file formats should be relatively easy to fix since most zip software allows for splitting zip files and supports extracting files out of split zip archives.