[go mode] Allow underscore separators in numbers

Closes codemirror#7059

Author: marijnh

mode/go/go.js

@@ -46,11 +46,11 @@ CodeMirror.defineMode("go", function(config) {
     }
     if (/[\d\.]/.test(ch)) {
       if (ch == ".") {
-        stream.match(/^[0-9]+([eE][\-+]?[0-9]+)?/);
+        stream.match(/^[0-9_]+([eE][\-+]?[0-9_]+)?/);
       } else if (ch == "0") {
-        stream.match(/^[xX][0-9a-fA-F]+/) || stream.match(/^0[0-7]+/);
+        stream.match(/^[xX][0-9a-fA-F_]+/) || stream.match(/^[0-7_]+/);
       } else {
-        stream.match(/^[0-9]*\.?[0-9]*([eE][\-+]?[0-9]+)?/);
+        stream.match(/^[0-9_]*\.?[0-9_]*([eE][\-+]?[0-9_]+)?/);
       }
       return "number";
     }