Issue1783554

This is a full implementation of CPython's zipimporter. It replaces our ZipFileImporter, which actually predates CPython's zipimporter that stemmed from PEP 302

Notes:

o ZipFileImporter was removed. It's possible we could remove SyspathArchive in the future, if we can make SyspathJavaLoader not rely on it (SyspathArchive is pretty lame)

o ZipImportException is initialized during exceptions.classDictInit when built in exceptions are initialized during startup. It has to be initialized as early as possible, but has to be done with a current PyFrame (which exceptions.classDictInit fakes to create its own exceptions)

o zipimporter creates the PyCode, then sets __loader__ and __path__ on its PyModule, then executes the PyCode. This is to match CPython's behavior. ZipFileImporter was lazier about this (resulting in some potential bugs). A couple imp methods were made public/split into two methods from one to support this

test_zipimport.py needs some work (e.g. it should test loading $py.class instead of .pycs). I haven't fixed it yet because it's relying on the marshal module, which is broken

applied in r3462-3