Revert "Add missing Sparkle.pch (osx)"

This reverts commit 4144437782349c319d88465bdd97ab3f189d9a20.
Revert "Fix sparkle build (osx)"

This reverts commit a40fd042b6d6cb3b01122d5df0f6947f527207a1.
Revert "Add sparkle framework, fixes #268"

This reverts commit a3e5ed1925f7e4e294cf7ce743795c2ee66411be.