common, DRM, a good API in the making

Big day today--cleaned up common. ICommonObject now has two sub-interfaces: ICommonElement and ICommonHandle. And a lot of spurious methods have been removed. Common is now the basic API for AgileWiki, though I still need to spend some time on the javadocs.

Tonight I also found some time to extend the DRM a bit. One small milestone achieved: Display now works with the DRM. Its a good start anyways, though there's still pleanty of work left to do here before going on to queries.

Overall I am delighted with how the common package is turning out. Interfaces usually drive me nuts, with either too many internal methods, too much casting when using them, or both. But I finally got it right. These are clean interfaces, and easy to use with very little casting. The final determining factor for acceptance then will be the quality of the javadocs. This is well worth the time spent, as a good API is critical. Indeed, there is nothing harder than creating an API that is good enough to be acceptable by other programmers. Too many otherwise great projects fail because the API stinks.