[Feature request] Create a map from a map

[matthew-dean]

In JS / TS, it's trivial to create a map from another map. That is:

let original = new Map()
let clone = new Map(original)

I didn't see this in the BiMap documentation, so I'm assuming this capability does not exist? I was going to use this library, but it looks like map cloning is non-trivial without spreading through an iterator, whereas JS map cloning is theoretically lower-cost in a JS engine. Can you add this capability?

let original = new BiMap()
let clone = new BiMap(original)

[Yomguithereal]

Most of mnemonist structures have a from static function to create them from other structures. Doesn’t BiMap.from(map) achieve what you want?