Renaming "aggregate" to "collect"

[vitaly-t]

Should we rename operator aggregate to collect?

These are just synonyms in the context of this library, both are semantically correct.

Here's some context, to better understand what's behind values aggregation.

[vitaly-t]

In TypeScript, one can simply rename it within the import statement:

import {aggregate as collect} from 'iter-ops'

Therefore, closing.