1) External developers who want to support purr-data (pd-l2ork) can #ifdef their guis.

2) For those who don't want to learn a new toolkit, and for unmaintained libraries, it'll be up to purr-data developers.

Until we have good documentation for integrating pd+nwjs, the first option may only work well for people who have a toe in both pools. I think that's me for cyclone, and I'll be glad to support purr-data directly in the new cyclone library as soon as I have a good chunk of time to do it, and some time to work out the kinks with Jonathan.