When completing Objective-C instance method invocations, perform a contextual conversion to an Objective-C pointer type of the target expression if needed. This fixes code completion of method invocations where the target is a smart pointer that has an explicit conversion operator to an Objective-C type.
CommandLine: Exit successfully for -version and -help

Tools that use the CommandLine library currently exit with an error
when invoked with -version or -help. This is unusual and non-standard,
so we'll fix them to exit successfully instead.

I don't expect that anyone relies on the current behaviour, so this
should be a fairly safe change.