External entities are no longer parsed in appcasts: pre-10.7, we use the "tidy" option for XML document parsing, which happens to behave this way, and in 10.7+ we use a new explicit option for this behavior.
This fixes pathToRelaunchForUpdater by supporting an executable path other than the host bundle path.
…ian so Xcode doesn't show warnings.
…y default. Fixes #133.