Remove dist files from source control

[rreusser]

Dist files have not been rebuilt in a long time. I think they should be removed from source control and only published in the npm module, especially since there is nothing (a test, a script run on push) to enforce they are actually built. The result is that they're present but likely to be wrong.

To remove friction, I've elected to preserve the type definitions in dist, though they could be moved to a types directory.

The files are still published to npm and may be retrieved from: https://unpkg.com/browse/regl/dist/

If this causes any problems (people retrieving outdated source files directly from github???), it can be reverted.

[rreusser]

Oh, I see the typescript build process just cps from ./ to ./dist. I'm just going to remove it from dist as well then. I'm not aware of a good reason anyone should be relying on dist/ of the git repo rather than obtaining dist from a more reliable source like npm or unpkg, but please correct me if I'm wrong and it can easily be restored.