Changing ```input``` to ```textarea```

To enable multiline, we should have a ```textarea``` element instead of
an ```input``` element
Adding multiline logic

```SHIFT + ENTER``` triggers multiline.

If triggered from false, enter in multline mode. Else, send the
statement. If only ```ENTER``` was sent and multiline is *off*, also
send the statement.

### Example: Building a function
```php
function foo () { <SHIFT + ENTER>
    echo 'bar'; <ENTER>
    echo 'baz'; <ENTER>
} <SHIFT + ENTER>
```
Merge branch 'feature/#7-Multiline-Support' into develop

Fixes #7