Columns that have no filters create whitespace in the filter section

[the-last-byte]

It would be expected that a column with no filter will not create an empty section in the layout.

final sortablegrid.SDGField relatedToField = new sortablegrid.SDGField(
			FIELD_ID_RELATED_TO,
			'Related To',
			'What.Name',
			'STRING',
			'',
			true,
			false,
			false,
			null,
			2
		);
		final sortablegrid.SDGField activityDateField = new sortablegrid.SDGField(
			FIELD_ID_ACTIVITY_DATE,
			'Due Date',
			'ActivityDate',
			'DATE',
			'',
			true,
			false,
			false,
			null,
			3
		);
		final sortablegrid.SDGField statusField = new sortablegrid.SDGField(
			FIELD_ID_STATUS,
			'Status',
			'Status',
			'PICKLIST',
			'',
			true,
			true,
			false,
			null,
			4
		);
		final sortablegrid.SDGField assignedToField = new sortablegrid.SDGField(
			FIELD_ID_ASSIGNED_TO,
			'Assigned To',
			'Owner.Name',
			'PICKLIST',
			'',
			true,
			true,
			false,
			null,
			5
		);

[the-last-byte]

@flindsaySFDC I am happy to put out some fixes - but the pull request will need to be answered and approved.