Persist changes to dock pane arrangement #56
Description
Commit 31c4b9d added support for saving pane visibility between sessions, so that a pane which was closed or autohidden will retain that state when the IDE is closed and started again. This goes a long way toward de-cluttering the UI, particularly with many plugins active.
This issue is for a full implementation, where if panes are moved around to different places, they should return to those locations after restarting.