Split input into buffer sized chunks

Input chunks from the client exceeding the buffer size would get
truncated. Now we communicate the size of the buffer to the webtty and
it will split the input into buffer sized chunks.

Fixes #1.

js/dist/webtty.d.ts

@@ -9,6 +9,7 @@ export declare const msgPong = "2";
 export declare const msgSetWindowTitle = "3";
 export declare const msgSetPreferences = "4";
 export declare const msgSetReconnect = "5";
+export declare const msgSetBufferSize = "6";
 export interface Terminal {
     info(): {
         columns: number;
@@ -43,6 +44,7 @@ export declare class WebTTY {
     args: string;
     authToken: string;
     reconnect: number;
+    bufSize: number;
     constructor(term: Terminal, connectionFactory: ConnectionFactory, args: string, authToken: string);
     open(): () => void;
 }