Adding support of nesting TableHeaderColumn. Merge their props.

[IgorZh]

If I wrap TableHeaderColumn BootstrapTable read props only of wrapper, but don't read props of wrapped TableHeaderColum. This PR fix that behaviour.

[philipp-sorin]

Yeh, this one is kinda helpful

[AllenFang]

@IgorZh Thanks for contributions, I will review it, BTW, could your please show me your use case? thanks

[IgorZh]

Hi, @AllenFang, thanks for your response. Here is my case. In need to use react-bootstrap-table table with redux-form.
I created TableHeaderColumn wrapper like this

class TableHeaderHeaderColumnField extends React.PureComponent {
  render() {
    return (
	<TableHeaderColumn
          {...this.props}
	  dataFormat={this.renderField}
       />
    );
  }

  renderField = (value, row, formatExtraData, rowIdx) => {
    const {
      name,
      tableName,
    } = this.props;

    return (
	<Field
          {...this.props}
	  name={`${tableName}[${rowIdx}].${name}`}
       />
    );
  };
}

and then use use it like this. I define redux-form props directly in HeaderColumnViewEditField

<BootstrapTable>
	<HeaderColumnViewEditField>
                name='description'
                component={Text}
		{t('description')}
	</HeaderColumnViewEditField>
</BootstrapTable>

[philipp-sorin]

@AllenFang Hey, I am really sorry but how fast can you review it, this issue is a blocker for my project as well :)

[AllenFang]

@philipp-sorin I'll release in this couple day.

[AllenFang]

This PR was released on v3.5.0, thanks your contributions.