ed7314933086b6069f4c1ab44b73946e0226e53a Typescript: Tighten up the t…

…ypes for `-init headerCallback` and other functions.

https://datatables.net/forums/discussion/comment/237183/#Comment_237183

6972c68c8dd9612657d17bb1268958152e101ec8 Typescript: Correct `-init language.aria` types

https://datatables.net/forums/discussion/comment/237181/#Comment_237181

Sync to source repo @6972c68c8dd9612657d17bb1268958152e101ec8

datatables.json

@@ -14,5 +14,5 @@
     ],
     "src-repo": "http://github.com/DataTables/DataTablesSrc",
     "last-tag": "2.1.8",
-    "last-sync": "2f8c2558a6a68f40e2c553a63764a9a98cc3d5c8"
+    "last-sync": "6972c68c8dd9612657d17bb1268958152e101ec8"
 }