Fixed empty value extension to handle 0 values.
Merge pull request #25 from norzechowicz/fix

Fixed empty value extension to handle 0 values.
Fixed value_format option type
Merge pull request #26 from norzechowicz/dev

Fixed value_format option type
Expanded symfony action column. Added url_attr and content options.
Added expanded example of content and url_attr options usage in action column
Merge pull request #27 from norzechowicz/dev

Expanded symfony action column.
Added hasColumnType to DataGridViewInterface
Added helper method to getIndexes to DataGridView
Merge pull request #28 from norzechowicz/dev

Added hasColumnType to DataGridViewInterface
Added batch column type
Added default options to batch column type
Merge pull request #29 from norzechowicz/batch

Added batch column type