Finish Register class (issue #3)

added events and trace functions to Register class

Details of additions/deletions below:
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Added:      doc/Events.md
            -- Added --
                list of events in ClassKernel

Modified:   Base/Register.php
            -- Updated --
                initialize check that event class exists and if exist set $eventDisabled to false
                getObject added event and trace handling
                getSingleton added event and trace handling
                _setObject added event and trace handling
                callEvent changed name of event class