user: filter out duplicate follow requests

Closes #228

See merge request pleroma/pleroma!263

formatter: preserve case of hashtags

Closes #165

See merge request pleroma/pleroma!262

when generating hashtag links, we used the casefolded version that we use in
the link URLs, instead of the original version.

accordingly, adjust the formatter to use the original text for the links, while
keeping the casefolded version for the URLs.

activitypub: actually send digest header when federating

See merge request pleroma/pleroma!261

this is needed for backwards compatibility with non-digest pleroma instances

digest signature validation

See merge request pleroma/pleroma!260

activitypub: verify remote http signature digests by recomputing the digest and replacing the digest header

Feature/filter exif (  solve #187 )

See merge request pleroma/pleroma!237

Articles/Notes with a actor list outside object

See merge request pleroma/pleroma!252

ostatus: return AS2 objects on /notice and /activities URLs like with /objects.

Closes #206

See merge request pleroma/pleroma!251

serverside frontend configuration

See merge request pleroma/pleroma!256

Feature/media description

Closes #174

See merge request pleroma/pleroma!255

mastodon api: support descriptions in media api, add PUT endpoint for updating metadata about a media upload

Mastodon does not use the object name as alt text when the object is an Image.

The code here is copied from feature/peertube by lain.

Co-authored-by: lain <lain@soykaf.club>

object normalization

See merge request !238

[Pleroma.Web.Nodeinfo.NodeinfoController]: add mediaProxy metadata

Closes #229

See merge request !235

activitypub: more robustly handle object-to-actor associations

See merge request !250

message summary

See merge request !249