DDMsgReader: When changing sub-boards, now supports cycling through sort options via [ and ] (for nelgin). Also, new scrolling window for help text for changing sub-boards.

DDMsgReader: When changing sub-boards, now supports cycling through sort options via [ and ] (for nelgin). Also, new scrolling window for help text for changing sub-boards. When changing to another sub-board, the user can now cycle through the sort options with the [ and ] keys. Also, updated the change sub-board help to show in a scrollable window for users with ANSI terminals, rather than simply displaying the help with a pause at the end. Other help screens could potentially be shown this way too. New theme configuration options: helpWinBorderColor and scrollingWinHelpTextColor