No real changes, just refactor wxEventLoop/wxApp::ProcessIdle().

No real changes, just refactor wxEventLoop/wxApp::ProcessIdle().

Old code called wxApp::ProcessIdle() from wxEventLoopManualRun::Run() which called wxEventLoop::ProcessIdle() which called wxApp methods from it. In the new version wxEventLoopManualRun::Run() calls wxEventLoopManualRun::ProcessIdle() which calls wxApp::ProcessIdle() which calls other wxApp methods which seems to make more sense and also allows overriding ProcessIdle() in either wxEventLoopManual or wxApp-derived classes.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61441 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775