Version 1.0.1

Bug fix: fixes an issue inherent with this library file being used by
multiple plugins in the same WordPress install.  Because multiple
plugins could instantiate this class, and all used the same message id
(nonce of __FILE__) the first object to be instantiated would get and
clear the messages regardless of whether they were added or needed by a
different client of the class.  The solution is to allow the message id
to be passed into the constructor, thereby allowing clients to set
messages that only they will retrieve/clear