Introduce the interface manager as a sub library.

This will want splitting out for other matrix bots to use eventually.
MatrixInterfaceCommand needs decoupling from Mjolnir and then it will
be added too.

src/commands/interface-manager/CommandReader.ts

@@ -4,7 +4,7 @@
  */
 
 import { UserID } from "matrix-bot-sdk";
-import { MatrixRoomReference } from "../models/MatrixRoomReference";
+import { MatrixRoomReference } from "./MatrixRoomReference";
 
 /**
  * Helper for peeking and reading character by character.

test/commands/CommandReaderTest.ts

@@ -1,6 +1,6 @@
 import expect from "expect";
-import { Keyword, readCommand, ReadItem } from "../../src/commands/CommandReader";
-import { MatrixRoomReference } from "../../src/models/MatrixRoomReference";
+import { Keyword, readCommand, ReadItem } from "../../src/commands/interface-manager/CommandReader";
+import { MatrixRoomReference } from "../../src/commands/interface-manager/MatrixRoomReference";
 
 describe("Can read", function() {
     it("Can read a simple command with only strings", function() {