Here's the next round of the series. In addition to the changes proposed by 宋文武, I homogenized the phases of the compiled packages, in order to simplify transformations. I also added a package transformer system similar to package-with-python2. Finally, I decided to have all packages bundle a copy of their source, and use it while building, rather than using the source packages as a build input, which had some complications.
Further comments are appreciated. Thanks, -- Andy