View source for CDT/Obsolete/ScannerDiscovery61/DougThoughts

Here's my current thinking, just a brainstorm of ideas.

* There are too many layers between IScannerInfo and the places where that info get's generated.
* We should be able to ask the build model for scanner discovery information.
* We should be able to find the compiler ITool for a given source file and ask it for it's IScannerInfo.
* Tool chain providers could then participate in that.
* Still need framework for build output parsing, maybe with the help of the ITools, but at least make the collected info available to them.
* Could add in other frameworks for things like dwarf.