Refs #5887. Introduces djConfig.afterOnLoad: if set to true, then dojo._loadInit will be fired after a 1 second timeout. Using a shorter timeout (100ms) had problems where the dojo._loadInit was fired before all modules were downloaded. That seemed odd given the synchronous XHR calls. Also because of a bug in the dependency mapping stuff, had to rearrange how _base.js is organized. Testing on supported browsers looks good, although Opera in the xdomain case seemed to have a problem. Still need to investigate that a little more, and then write up release notes on the djConfig option.
