modularized twoFrameBrowser

BrowserWindow.css describes the style of the
browser window
BrowserWindow.js declares a class BrowserWindow and some
helper functions that take care of the client side code
and we added a template tag that will set up the html and a little
bit of javascript needed to actually create the window. Inheriting from
twoFrameBrowser takes care of the necessary js and css inclusions.
added some routines to allow client to access BrowserWindow