Adding support for subpaths

[Thatoo]

For what I understand, the matrix protocol requires matrix media repository to start with /_matrix/media, sub-paths are unfortunately not possible.
And this is forbidding file hosting project such as Nextcloud to become a matrix media repository and thus forbid riochat (Element for Nextcloud) to "Add matrix share" and truly integrate Element within Nextcloud.

For what I understand : the spec doesn't allow subpathing given all the paths are defined as /_matrix, and thus are absolute.
Treating them as absolute is overly restrictive, isn't it?

It makes a problem for media repository (mentioned above) but also for Pusher.

Would it be possible to change the spec in order to make subpaths discovering in .well-known files?

[turt2live]

Resolving #693 I think will resolve this issue, or at least provide a better direction for such an improvement request.