perf: remove regexp-clone

[Uzlopak]

Cloning an regexp does not need an external library.

[AbdelrahmanHafez]

Glad that we're getting rid of more and more dependencies.
Have a couple of questions and suggestions regarding the introduced changes, but I'm happy with that change.

[Uzlopak]

@AbdelrahmanHafez
Fixed the comments.

[Uzlopak]

@AbdelrahmanHafez
@vkarpov15
Also here some benchmarks:

regexp-clone x 2,177,401 ops/sec ±1.10% (87 runs sampled)
new RegExp(regex) x 4,872,620 ops/sec ±0.74% (91 runs sampled)
new RegExp(regex.source, regex.flags) x 5,274,696 ops/sec ±0.73% (89 runs sampled)

So intuitivly, we have implemented the fastest cloning

const Benchmark = require('benchmark');
const cloneRegExp = require('regexp-clone');

const regex = /^a$/g;

new Benchmark.Suite()
  .add('regexp-clone', function () {
    const newRegex = cloneRegExp(regex)
  })
  .add('new RegExp(regex)', function () {
    const newRegex = new RegExp(regex);
    if (typeof regex.lastIndex === "number") {
        newRegex.lastIndex = regex.lastIndex;
    }
  })
  .add('new RegExp(regex.source, regex.flags)', function () {
    const newRegex = new RegExp(regex.source, regex.flags);
    if (typeof regex.lastIndex === "number") {
        newRegex.lastIndex = regex.lastIndex;
    }
  })
  .on('cycle', function (evt) {
    console.log(String(evt.target));
  })
  .run();

[vkarpov15]

Nice, thanks 👍 I also agree about removing deps.