Removal of the PropertyList class, since the approach allowing a [0 ... n] cardinality for Attribute instance has been abandoned
(see comment in commit 1593149 for more details). The case of PropertySingleton still needs to be re-evaluated.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK8@1593151 13f79535-47bb-0310-9956-ffa450edef68