Add BigInt support

lib/build.js

@@ -117,6 +117,9 @@ function walk_obj(next, next_child) {
     tag_type = (next % 1 === 0) ? 'integer' : 'real';
     next_child.ele(tag_type).txt(next.toString());
 
+  } else if ('BigInt' == name) {
+    next_child.ele('integer').txt(next);
+
   } else if ('Date' == name) {
     next_child.ele('date').txt(ISODateString(new Date(next)));
 

package.json

@@ -38,6 +38,6 @@
     "test": "make test"
   },
   "engines": {
-    "node": ">=6"
+    "node": ">=10.4.0"
   }
 }

test/build.js

@@ -40,6 +40,17 @@ describe('plist', function () {
 */}));
     });
 
+    it('should create a plist XML real from a BigInt', function () {
+      var xml = build(BigInt('0x1fffffffffffff'));
+      assert.strictEqual(xml, multiline(function () {/*
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+  <integer>9007199254740991</integer>
+</plist>
+*/}));
+    });
+
     it('should create a plist XML date from a Date', function () {
       var xml = build(new Date('2010-02-08T21:41:23Z'));
       assert.strictEqual(xml, multiline(function () {/*