Rename the `import` method

[martines3000]

Hi.

We are developing a project that is running inside a hardened JavaScript environment called SES (Secure EcmaScript). SES doesn't allow overriding “reserved” keywords like import and this causes many issues for us.

My suggestion is to maybe rename the import() method to importStream(). This way we we avoid using a "reserved" keyword and also make it clearer what the method does. I hope this is not too large of a change and that it can be done. Thanks.

Issue that was opened on the library that implements this spec: rdfjs/N3.js#380

[elf-pavlik]

Since this is a breaking change, it would make sense to consider all other proposed breaking changes and implement them simultaneously. This would require all the implementations to undergo a major release.