Arrays

This pull request implement arrays on storage vectors  (raw Javascript arrays). Strings and vectors are arrays. So you can do something like:

```
(make-array 100 :element-type 'character :initial-element #\.)
```

Multi-dimensional arrays and fill pointer need to be implemented too.

It slows down the performance very much because the compiler relies heavily on string manipulation, which is not primitive anymore. But it is not very important now.  The new compiler will help with it.

Please, have a look and give feedback.  Thanks.