[Slate] Add Editor Definition

Editor is not defined in @types/slate, making it difficult to develop
for slate in Typescript if not using slate-react ( and therefore
@types/slate-react, where the React mounted editor is defined).

types/slate/index.d.ts

@@ -7,10 +7,10 @@
 //                 Kalley Powell <https://github.com/kalley>
 //                 Francesco Agnoletto <https://github.com/Kornil>
 //                 Irwan Fario Subastian <https://github.com/isubasti>
+//                 Sebastian Greaves <https://github.com/sgreav>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.3
 import * as Immutable from "immutable";
-
 export class Data extends Immutable.Record({}) {
     [key: string]: any;
 
@@ -1527,4 +1527,22 @@ export interface PathUtils {
     ): Immutable.List<number>;
 }
 
+export class Editor extends Immutable.Record({}) {
+  object: "editor";
+  onChange: (change: Change) => void;
+  plugins: any[];
+  readOnly: boolean;
+  value: Value;
+
+  change(customChange: (change: Change, ...args: any[]) => Change): void;
+  command(name: string, ...args: any[]): void;
+  event(handler: string, event: any): void;
+  query(query: string, ...args: any[]): any;
+  registerCommand(command: string): void;
+  registerQuery(query: string): void;
+  run(key: string, ...args: any[]): any;
+  setReadOnly(readOnly: boolean): Editor;
+  setValue(value: Value, options?: object): Editor;
+}
+
 export {};

types/slate/slate-tests.ts

@@ -1,4 +1,4 @@
-import { Value, Data, BlockJSON, Document } from "slate";
+import { Value, Data, BlockJSON, Document, Editor, Change } from "slate";
 
 const data = Data.create({ foo: "bar " });
 const value = Value.create({ data });
@@ -45,3 +45,16 @@ const doc = Document.fromJSON({
 	data: {},
 	nodes: [node]
 });
+
+const editor = new Editor({ value });
+editor.change((change: Change) => {
+	return change.insertText("test");
+});
+
+editor.registerQuery("testQuery");
+editor.registerCommand("testCommand");
+editor.setReadOnly(true).setValue(value);
+editor.command("testCommand");
+editor.query("testQuery");
+editor.run("testCommand");
+editor.event("mouseDown", () => { });