Ability to speed up render

[sergyperov]

There are some projects that takes quite long to finish "drawing" process, for example:

• https://verse.works/artworks/0ce696c3-d4e9-4745-ad37-c660600f8d86
• https://verse.works/artworks/280581b0-aaa1-4419-b390-a19a17917e7c

I do understand that sometimes it's just due to performance issues. Although would be nice to give ability for Platform to send a signal to Project indicating that we want to speed up render (if possible) to see the final version ASAP.

Actual use case: "Speed up" button on Artwork/Edition page to see final output (in case Project supports such speed up)

[gluonfield]

This can be done using signal as used in latest commit. But I think artists should also support universally used URL parameter for this such as fast=true.