Add standard chess pieces (#176)

Author: MDLC01

CHANGELOG.md

@@ -2,6 +2,22 @@
 
 ## Unreleased
 
+### New in `sym`
+
+- New `chess` submodule
+  - `king.white`: ♔
+  - `king.black`: ♚
+  - `queen.white`: ♕
+  - `queen.black`: ♛
+  - `rook.white`: ♖
+  - `rook.black`: ♜
+  - `bishop.white`: ♗
+  - `bishop.black`: ♝
+  - `knight.white`: ♘
+  - `knight.black`: ♞
+  - `pawn.white`: ♙
+  - `pawn.black`: ♟︎
+
 ### Removals in `sym` **(Breaking change)**
 These previously deprecated items were removed:
 - `gt.tri.*`

src/modules/sym.txt

@@ -733,6 +733,27 @@ suit
   .spade.filled ♠\vs{text}
   .spade.stroked ♤
 
+chess {
+  king
+    .white ♔
+    .black ♚
+  queen
+    .white ♕
+    .black ♛
+  rook
+    .white ♖
+    .black ♜
+  bishop
+    .white ♗
+    .black ♝
+  knight
+    .white ♘
+    .black ♞
+  pawn
+    .white ♙
+    .black ♟︎
+}
+
 // Music.
 note
   .up 🎜