UHC: registerPackage stop using source pkg and inplace args
UHC's version of registerPackage is the only one that makes use of the PackageDescription and inplace :: Bool args, and it's quite wrong for doing so. Registering a package should depend on the content of the InstalledPackageInfo and the PackageDBStack to register into and the Compiler to register with. It should not depend on the original source PackageDescription, and should not need a separate inplace arg. The location is determined by the PackageDBStack. UHC was not following this pattern and thereby forcing the general compiler independent registerPackage to take annoying and unnecessary arguments. With this patch, the register location is determined by the PackageDBStack. The source package id also comes from the InstalledPackageInfo rather than the source PackageDescription. This patch does not yet change the registerPackage type.