Add support for gogui_rules_board_gfx

Engines that support the gogui_rules_board_gfx gtp command can use it to display custom graphics in addition to stones. For instance, a chess program can use it to set square colors and piece labels. Analyze commands will display information on top of these gfx commands.

Fix missing dependency for gogui-display

v1.5.3

procedure

New features and fixes

• Don't use Quaqua anymore, which should fix some crashes on macOS (issue #18).
• Support for large boards up to 52x52.
• Support for games with moving pieces such as chess or ataxx
• Drag-and-drop of sgf files (thanks to @zakki)
• Fix wrong player names in sgf from gogui-twogtp -alternate (issue #9, thanks to @tomtseng)
• New gogui-rules_captured_count command.
• Minor fixes and improvements.

Bug fixes

• Correct sgf result written by gogui-twogtp -alternate (#9).
• Display other games' results.
• Keep gtp shell and analyze dialog opened after changing program.

Support other games

• GTP protocol extension to support alternative game rules (see doc)
• Wait a little for program output before displaying popup.
• Edit commands in Tree contextual menu.
• New menu item View / Icon Size