new field type table

Example:
![bildschirmfoto 2013-10-05 um 19 08 56](https://f.cloud.github.com/assets/761817/1275087/6d29c444-2de4-11e3-9e12-3be286852bac.png)

can be defined like

```
array(
                  'name'          => 'testtable',
                  'label'         => 'Test Table',
                  'type'          => 'table',
                  'args'          => array(
                    'columns' => array(
                    	array(
                    		'name' => 'range start',
                    		'type' => 'datepicker'
                    		),
                    	array(
                    		'name' => 'range end',
                    		'type' => 'datepicker'
                    		),
                    	array(
                    		'name' => 'price',
                    		'type' => 'int'
                    		)
                    ),
                  )
              )
```