implement case-insensitive search for groups in sharing dialog

increase whitespace below headings in settings

This reverts commit 0df070a8.

fix for issue #10483

reduce bottom padding in filelist, fix perceived glitching, fix #11213

fix position and style of sort indicator

Add CssImportFilter. More elegant fix for documents#348

Preview large TXT files fix

we also encrypt/decrypt files in the versions folder

we also encrypt/decrypt files in the versions folder for previews and if encryption is enabled/disabled

add /assets to gitignore

Bitmap class to handle all Imagick conversions to bitmap

Limit the size of the string generating the preview image for TXT files

Fix S3 copy and rename overwriting target directory

Redirect only to absolute URL

Use SVG previews for public sharing

Add flock to config

Fix PHPDoc

Remove invalid PHPDoc