Ability to specify extra environment variables during compilation #247
Description
It looks like markdown and potentially other grammars support enabling extensions or extra features during compilation through the use of environment variables. It would be really nice to have a built in way to provide extra environment arguments.
I am not sure how this would work with the current API that assigns a single grammar to a major mode. I could see it working as a selector between multiple supported grammars or just a way for the user to pass env vars to an existing grammar. I am happy to try to get either option to work, but wanted to discuss the direction and see if there was interest in supporting this feature.