Add d2 (#1091)

README.md

@@ -376,6 +376,7 @@ Cuda
 CUE
 Cython
 D
+D2
 DAML
 Dart
 DeviceTree

languages.json

@@ -361,6 +361,11 @@
       "nested_comments": [["/+", "+/"]],
       "extensions": ["d"]
     },
+    "D2": {
+      "line_comment": ["#"],
+      "multi_line_comments": [["\\\"\\\"\\\"", "\\\"\\\"\\\""]],
+      "extensions": ["d2"]
+    },
     "Daml": {
       "name": "DAML",
       "nested": true,

tests/data/d2.d2

@@ -0,0 +1,15 @@
+# 15 lines 4 code 6 comments 5 blanks
+
+# Comments start with a hash character and continue until the next newline or EOF.
+x -> y
+
+x -> y # I am at the end
+
+'#x' -> "#y"
+
+"""
+This is a
+block comment
+"""
+
+y -> z