Add transform profile

Add transform profile info about each plugin.

It should be enabled by `profile` option. (Default: `false`).

If `profile` option is enabled, transform should expose `profile` info in result object:

```json
{
"html": "...",
"profile": {


}
}
```

Profiler can affect performance.

Profiler should be platform agnostic.

Profiler should be implemented in transformer itself, not in each plugin.