Add noUnusedLocals tsconfig flag, fix issues

Two parts were commented out:
- _writeStopped: This is because _xoffSentToCatchUp references this variable
  and the feature is sort of half implemented/disabled.
- _clearChar: This is because some comments still reference this, it's part
  of the work needed to do better line redrawing.

src/utils/CharMeasure.test.ts

@@ -4,7 +4,7 @@
  */
 
 import jsdom = require('jsdom');
-import { ICharMeasure, ITerminal } from '../Types';
+import { ICharMeasure } from '../Types';
 import { assert } from 'chai';
 import { CharMeasure } from './CharMeasure';
 

src/utils/CharMeasure.ts

@@ -3,7 +3,7 @@
  * @license MIT
  */
 
-import { ICharMeasure, ITerminal, ITerminalOptions } from '../Types';
+import { ICharMeasure, ITerminalOptions } from '../Types';
 import { EventEmitter } from '../EventEmitter';
 
 /**

src/utils/CircularList.test.ts

@@ -6,10 +6,6 @@
 import { assert } from 'chai';
 import { CircularList } from './CircularList';
 
-class TestCircularList<T> extends CircularList<T> {
-  public get array(): T[] { return this._array; }
-}
-
 describe('CircularList', () => {
   describe('push', () => {
     it('should push values onto the array', () => {

src/utils/CircularList.ts

@@ -60,7 +60,6 @@ export class CircularList<T> extends EventEmitter implements ICircularList<T> {
 
   public get forEach(): (callbackfn: (value: T, index: number) => void) => void {
     return (callbackfn: (value: T, index: number) => void) => {
-      let i = 0;
       let length = this.length;
       for (let i = 0; i < length; i++) {
         callbackfn(this.get(i), i);

src/utils/TestUtils.test.ts

@@ -269,6 +269,9 @@ export class MockInputHandlingTerminal implements IInputHandlingTerminal {
   addDisposableListener(type: string, handler: XtermListener): IDisposable {
     throw new Error('Method not implemented.');
   }
+  tabSet(): void {
+    throw new Error('Method not implemented.');
+  }
 }
 
 export class MockBuffer implements IBuffer {