remove dojo/_base/connect and dojo/_base/event, plus fix dom-prop

dom-prop.js is using dojo.connect() and cannot be changed in the 1.x line
w/out a marginal break in back-compat, so changing it here instead.
remove dojo/_base/html and associated tests
remove dojo/_base/Deferred and associated tests
remove dojo/_base/query, NodeList and associated tests

Also, use dojo/NodeList rather than dojo/_base/NodeList in dnd/Selector.js.
remove dojo/_base/sniff and associated test
remove dojo/_base/xhr, dojo/io and associated tests
remove dojo/_base/json and associated test
remove dojo/behavior and associated tests
parser: remove dojoType etc.
remove firebug
remove unused function from dojo/html.js
remove dojo/cache and associated tests
don't implicitly load unrequested modules
remove code for sync mode from currency, i18n tests
remove dojo/ready and associated usages

breaks dojo/robotx.js; we need another way for the test file to signal that it's ready.
remove sync code from i18n
replace legacy loader with pure AMD loader
remove dojo/main, dojo/_base/browser
remove support for rhino, spider monkey
remove apparently obsolete firefox-extension code