Title for section, return new NSString.nil for no title

By default, this returns no title.

iOS callback: titleForHeaderInSection

Property definitions

ios $ TableView :: title_for_header_in_section
	# Title for `section`, return `new NSString.nil` for no title
	#
	# By default, this returns no title.
	#
	# iOS callback: `titleForHeaderInSection`
	protected fun title_for_header_in_section(view: UITableView, section: Int): NSString
	do return new NSString.nil
lib/ios/ui/ui.nit:563,2--569,27