Instead of passing the macro based Predicate to findUnmanaged it now
expects a function which can be passed to std::find_if.
Existing code like:
xcb_window_t window; // our test window
Unmanaged *u = findUnmanaged(WindowMatchPredicated(window));
becomes:
Unmanaged *u = findUnmanaged([window](const Unmanaged *u) {
return u->window() == window;
});
In addition an overload is added which takes the window id to cover
the common case to search for an Unmanaged by its ID. The above example
becomes:
Unmanaged *u = findUnmanaged(window);
The advantage is that it is way more flexible and has the logic what
to check for directly with the code and not hidden in the macro
definition.