Use tilde instead of JSON-LD context definition

[BANOnotIT]

@ and : have to be encoded in URI components which increases keys in final URI.

Might be a good idea to use ~ char to define IRI terms for example:

web+activitypub:cat~Hug?~cat=urn%3Acats&object=urn%3Ahuman%3Ashredinger&cat~name=Snowball
## web+activitypub:cat~Hug?~cat={urn:cats}&object={urn:human:shredinger}&cat~name={Snowball}