Enable Extending Editor types in TypeScript (#4133)

* Change HistoryEditor from type to interface

* v0.60.8

* v0.60.9

* Have ReactEditor and HistoryEditor extend BaseEditor instead of Editor

* v0.60.10

packages/slate-hyperscript/package.json

@@ -1,7 +1,7 @@
 {
   "name": "slate-hyperscript",
   "description": "A hyperscript helper for creating Slate documents.",
-  "version": "0.60.7",
+  "version": "0.60.9",
   "license": "MIT",
   "repository": "git://github.com/ianstormtaylor/slate.git",
   "main": "dist/index.js",
@@ -17,7 +17,7 @@
     "is-plain-object": "^3.0.0"
   },
   "devDependencies": {
-    "slate": "^0.60.7"
+    "slate": "^0.60.9"
   },
   "peerDependencies": {
     "slate": ">=0.55.0"