void return type.
([Invocation -invokeWithElement:]): Method removed.
([Invocation -invokeWithObject:]): Make is -subclassResponsibility.
([Invocation -getReturnValue:]): Make sure return_value is non-NULL.
([ArgframeInvocation -initWithArgframe:type:]): Use objc_calloc.
([MethodInvocation -initWithArgframe:selector:]): Try hard to get a
selector with a type string.
([MethodInvocation -initWithTarget:selector:...]): New method.
([MethodInvocation -invoke]): Get the target and selector properly.
([MethodInvocation -invokeWithObject:]): New method.
git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@898 72102866-910b-0410-8b05-ffd578937521
