* put a file without a generated preview in the trashbin
(e.g. a *.docx file)
* open the trashbin
* following errors will show up in the nextcloud.log:
- filesize(): stat failed for ...
- fopen(...): failed to open stream: No such file or directory at ...
- fread() expects parameter 1 to be resource, boolean given at ...
- fclose() expects parameter 1 to be resource, boolean given at ...
- imagecreatefromstring(): Empty string or invalid image at ...
This is because the preview code tries to load an SVG image, which
is obviously only text.
The fix simply handles this before the loading happens and the web UI
keeps showing the default mimetype icon.
We can't use an authoritive classmap in the current state as it would
kill app loading. However we can use a proper classmap for the normal
core stuff.
This introduces the defacto standard PSR-4 autoloader from composer into
core. This will allow proper PSR-4 naming of our classes.
Since our original autoloader is still available we can slowly switch
over classes to PSR-4.
