Fixes license header and adds stable sort

[RReverser]

For #1234.

[RReverser]

@zpao @benjamn Ping.

[RReverser]

Since there was no response from @zpao and others, this seems to be not relevant (most likely it even won't merge now), so I'm closing it.

[zpao]

Sorry for letting it hang. I may still come back to it, it's just been lower pri. I know @vjeux is still interested.

I was actually thinking about this again the other day when I was thinking of some other transform stuff. I'd be curious if we could use recast instead of escodegen (I vaguely remember you did at one point). That would result in leaving comments and such intact...

[RReverser]

Yes, that would be possible and I mentioned that in #1234 (comment), however you didn't reply anything at that point, so wasn't sure. I switched from recast to esprima+escodegen in pure-cjs as it improved performance in 4-5 times, but if you'd say this is the thing that you need, I could add using recast as separate option.

[RReverser]

@zpao With esprima+escodegen upgrades, added support for preserving comments in output via comments option in pure-cjs@1.10.