Bad wxSingleInstanceChecker example in help file

[koen at vermeer.tv]

Hi,

I just took a look at the example given in the help on
wxSingleInstanceCheck (wxWidgets 2.8.5) and it seems to contain (at least)
two bugs and/or inconsistencies with other parts of the help.

1. If OnInit() returns false, OnExit() isn't called. Hence, m_checker
isn't deleted, and memory is leaked.
2. OnExit() should return the value of the base class' member function. In
the example, it returns 0.

Best,
Koen