PEP8
Fix a bug with setting the active tabwidget when an editor contains tabs.

If an editor contains tabs, after certain operations (e.g., navigating
the editor tabs using keyboard shortcuts) a change in focus
sets the editor area pane `active_tabwidget` to one of those internal tabs,
rather than to the tab of the editor in the editor area.
Fix line after cut & paste.
Move qt-specific testing utils to pyface/ui/qt4/util .
Clean up test file.
Merge pull request #89 from enthought/fix-split-editor-area-pane-focus

Fix split editor area pane focus