document packaging of environments as self-extracting executables

[saraedum]

See #111.

TODO:

• Windows Examples (maybe later.)
• Package makeself for conda-forge

[dbast]

@saraedum This looks pretty good and makeself is available via conda-forge now. Any reason this is still a draft? (a windows example can also be added later via new PR).

[saraedum]

@dbast Sure. I think this can be merged. (@DunklesArchipel, we worked on the Windows bit of this at some point years ago. But I guess you also forgot how we actually managed to do this in the end. actually, it's documented in #111. But I don't think I have the time to write this down properly at the moment.)

[dbast]

@saraedum Thanks!