Fix wrong model recognition

Parser was recognizing words with `model` keyword combination, for example `` `model` `` or `Cmodel`, as model, this is a suggestion to fix the issue. this pull request would close issue #92 and #152.
With input:

```
identifier   model ( media type )
```

the output is 

```
Array
(
    [0] =>      identifier   model ( media type )
    [1] =>      identifier   
    [2] => identifier  
    [3] =>  ( media type )
    [4] =>  media type 
)
```

So 5 groups where identifier (if any) is at index 2 and media type (if any) is at index 4. Mind the leading / trailing spaces