Allow apps to extend or modify schemas

[andrewxhill]

Thinking through examples like the default schemas for MEDIA and CameraRoll.

1. Modify schemas in place.

A user may want to use one of those but modify the schema. For example, with CameraRoll, they may want their app to pin all versions of the sampled photo.

Likewise, another app may join that thread and decide it doesn't want to pin any, even though the schema is instructing the node to.

In both cases, the schema is the same, just app or user-specific instructions should be possible.

2. Extending schemas.

Imagine I build an app with the MEDIA schema, but I also want to include another sample at 10px x 10px. Any thread i create with my new schema is actually still MEDIA compatible.

This idea popped up trying to scope out the photos connector, because you don't want all these obviously compatible threads floating around that aren't usable together.

[andrewxhill]

probably better in go-textile repo. moving