function _callHandler(handler) {
        try {
            // TODO (issue 1034): We *could* use a $.Deferred for this, except deferred objects enter a broken
            // state if any resolution callback throws an exception. Since third parties (e.g. extensions) may
            // add callbacks to this, we need to be robust to exceptions
            handler();
        } catch (e) {
            console.error("Exception when calling a 'brackets done loading' handler: " + e);
            console.log(e.stack);
        }
    }
Defines hooks to assist with module initialization.

This module defines 3 methods for client modules to attach callbacks:
   - htmlReady - When the main application template is rendered
   - extensionsLoaded - When the extension manager has loaded all extensions
   - appReady - When Brackets completes loading all modules and extensions

These are *not* jQuery events. Each method is similar to $(document).ready
in that it will call the handler immediately if brackets is already done
loading.