bug copying .gif files to preview

[eelucio]

this fix solves this bug. I added GIF to the IMAGE_RESIZE_EXCEPTIONS = ["PDF", "HDF5", "GRIB", "GIF"] so the files with this extension will be copied instead of resized.

E.g. .mp4 files were copied because they were neither in that list nor they were recognised by Image.registered_extensions()

everything else are minor typo/punctuation fixes.

To be merged after the history flag branch has been merged.

[eelucio]

Okey,

With the last commit 8970ad3efb770320bc11140f4aadc7cf9e6a4118 we tried to exploit get_history() to the fullest.

Until now it used to be passed with user=None from _history always, now it can be:

• either be called with user=User() when we want to search own history
• or called with user=None to search history of everyone (including self).

Thanks for your patience and interest @MoSHad91 :)

for what we checked it should not break regular functionalitiy.

NOTE: limited to all or self, cannot pinpoint specific users. For that we would need to figure out how to pass the user object of the username because the username string itself does not work