Re-arrange code in X11Window::restackWindow()
Above and Below modes should be handled as follows:
if (sibling) { workspace_stack_below/above(window, sibling); } else { workspace_lower/raise(window); }
But with the current code, it's difficult to see. This change rearranges the code in the restackWindow() so it's more clear how the Above and the Below modes are implemented.
It also moves workspace()->findClient(Predicate::WindowMatch, above); to the top because all branches have it.