Add query-panel repository

[kjetilk]

The requirement to have a SPARQL-based patch system to the PATCH method, is discussed in solid/specification#125 , but is spawning many different repositories, and also has connections to the W3C SPARQL 1.2 CG.

I think we would have a more focused effort on this topic if we activate the already existing query panel. However, it extends beyond the existing solid-tpf repository, and so, I suggest we add a query-panel repository as encouraged by the current process.

[RubenVerborgh]

However, it extends beyond the existing solid-tpf repository,

That one is just a piece of prototype code; it should probably be archived and stay as-is.

[justinwb]

The query-panel repository has been created, along with peripheral requirements (panel team, gitter channel, etc.)