installPackage doesn't do anything, without loading the OFS configure.zcml first. The ZopeLite layer doesn't know anything about ZCML, so we rather defer the setup to consumers.

Register OFS as a package and give it an initialize function. Moved registration of OFS classes there from Products.OFSP.

No longer create an `Extensions` folder in the standard instance skeleton. External methods will become entirely optional in Zope 2.14.