Allow ECMAScript module syntax

[BurtHarris]

It would be a good idea to permit ECMA-style import and export statement in macro files

[BurtHarris]

I may be on the track of this one, using require() vs. include() in the extension.

[BurtHarris]

Hmm. If someone wants to write their macros using the ECMA module syntax, they may need to name the javascript in a .mjs file. Based on what I read, CommonJS modules can import ECMA modules, but not the other way around.