turned Query into a class

[jimmywarting]

got surprised that it still runs fine after mostly auto converting it using vscode
had to make few minor adjustment, added a proxy to make it still work without using new keyword
also got rid of inherit

[vkarpov15]

I would strongly prefer to not export a proxy here, that seems like an unnecessary perf impact.

A couple of alternatives that we can consider:

1. Implement a class QueryBase { ... }, and then create a function that inherits from that class:

class Base {
  constructor(name) {
    this.name = name;
  }

  sayHi() {
    console.log(`Hello, ${this.name}`);
  }
}

function Child(name) {
  if (!(this instanceof Child)) {
    return new Child(name);
  }
  this.name = name;
}

Child.prototype = Object.create(Base.prototype);
Child.prototype.constructor = Child;

const c = Child('World');
c.sayHi();

2. Put this in a breaking change, and perhaps add a separate mquery.new() function that allows creating a query instance without using the new operator.

[jimmywarting]

I would not have anything against a major change.
mquery.new() seems a bit unnecessary...? and abnormal? in that case we can just say: hey use new Query() instead?

[jimmywarting]

I would strongly prefer to not export a proxy here, that seems like an unnecessary perf impact.

Is it really impacting the perf that much?