Show the order in which different event handlers are called.

Show the order in which different event handlers are called.

Update the event sample to define (as) many (as possible) event handlers for a
test button and log messages in all of the handlers to leave a trace of the
order in which they were executed.

Add a pointer to this feature of the event sample to the events overview.

Closes #11156.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61852 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775