Even simple usage possible

Hi, I think the usage of this library could be simpler:

``` python
import json262 as json

#... old code comes here (unchanged) :-)
```

I don't know it is difficult to implement it this way.

Or do reasons exist why this is not a good idea?

Start by reviewing the proposed `import json262 as json` usage and the library's current import entry point. Determine whether making the package usable as a drop-in `json` replacement is feasible without changing existing behavior, and define compatibility tests that show the simpler import works.

Written by the indexing model from the issue text.