What about moving the build/* files into the new runtime folder?

[Jacopo Cappellato]

Now that we have the new "runtime folder", containing all the runtime 
objects, what about moving all the build/* files from each component 
into a new runtime/build/ folder?

In this way the only folder in which there will be files written while 
building/running the system will be in the runtime folder.

I see advantages in this approach, especially for the distribution of 
pre-built releases: the pre-built release could be simply the source 
official release + the pre-built objects in the runtime folder.
Also everything apart from the runtime folder could be in a read-only 
file system (for example a cd).

Jacopo