Commits for Chessboard Renderer

Issue #1269424 by Eric_A: Added support for "9" and "10" in empty squares notation.

Issue #1589634 by Eric_A: Untangled empty square handling and row-file handling.

Issue #1589082 by Eric_A: Untangled sanitizing and parsing.

Issue #1366556 follow-up by Eric_A: Added explicit handling of default chessboard settings.