Switcher now works as expected.
* Renamed TRoster::ActivateApp() to UpdateActiveApp(), as the app is already activated
at that point (the registrar only keeps track of it).
* BWindow::DispatchMessage() now calls the new BRoster::Private::UpdateActiveApp()
method when it receives a B_WINDOW_ACTIVATED message.
* Added BRoster::_UpdateActiveApp() which calls the new B_REG_UPDATE_ACTIVE_APP.
* Removed now unused B_REG_ACTIVATE_APP.
* Minor cleanup.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@19857 a95241bf-73f2-0310-859d-f6bbb57e9c96