Adding a javascript model to represent the spec and a renderer to display it.

This adds a sdk to manipulate more easily the output of VarDebug in json mode and a renderer that works with it.

Here's a sample :

```javascript
var json = {"_":"1:array:7","n`0": 1,"n`1": 1,"n`2": ["a","a","R`7:6"],"n`3": 2,"n`4": "R`9:8","n`5": "R`10:3","n`6": "R`11:6","__refs": {"6":[-7,-11],"8":[-9],"3":[-10]}};
var dictionary = new VarDebug.Dictionary();
dictionary.fromJson(json, function(dictionary) {
    console.log(dictionary.getEntryPoint());
});
```

This should output :

```
VarDebug.PhpArray {traversable: true, attrs: Array[7], keys: Array[7], cutBy: undefined, isEmpty: function…}
```

We can now work with this, let's imagine we stored it in a var `entity` :

```javascript
if (entity instanceof VarDebug.PhpArray) {
    for (var i in entity.attrs) {
        console.log(entity);
    }
}
```

This should output :

```
VarDebug.PhpScalar {traversable: false, utf8: true, cut: 0, value: 1, type: "int"…}
VarDebug.PhpScalar {traversable: false, utf8: true, cut: 0, value: 1, type: "int"…}
VarDebug.PhpArray {traversable: true, attrs: Array[3], keys: Array[3], cutBy: undefined, isEmpty: function…}
VarDebug.PhpScalar {traversable: false, utf8: true, cut: 0, value: 2, type: "int"…}
VarDebug.PhpReference {traversable: true, position: "9", ampersand: 7, resolve: function, index: 8}
VarDebug.PhpReference {traversable: true, position: "10", ampersand: 2, resolve: function, index: 9}
VarDebug.PhpReference {traversable: true, position: "11", ampersand: 5, resolve: function, index: 10}
```

To play with the renderer :

```html
<h2>debug()</h2>

<link rel="stylesheet" href="path/to/assets/css/var_debug.css" />
<script src="path/to/assets/js/sdk.js"></script>
<script src="path/to/assets/js/rendering.js"></script>
<script src="path/to/assets/js/core.js"></script>

<div id="dumper-content">

</div>

<script>
    var json = {"_":"1:array:7","n`0": 1,"n`1": 1,"n`2": ["a","a","R`7:6"],"n`3": 2,"n`4": "R`9:8","n`5": "R`10:3","n`6": "R`11:6","__refs": {"6":[-7,-11],"8":[-9],"3":[-10]}};
    VarDebug.run(json);
</script>
```

Todo sdk
--------

- [ ] Full documentation of the sdk
- [ ] Javascript unit tests ?
- [x] Dedicated type for resources (streams, mysql connections...). Currently handled as a PhpObject.
- [x] Refactor the code, some names are not explicits nor fully matching the purpose of the function/class.

Todo renderer
-------------

- [ ] Use the same colors as the VarDebug CLI.
- [x] Display more informations on hover.
- [x] Multi-line strings and collapse button for better readability.
- [x] Refactor the code, too much nested calls.