Class for managing ticks. When a set of plots shares a common column and axis setting, they should all use the same ticks. The other problem this should fix is when a stack of plots all have heights within a couple of pixels of one another, we should try to use the same ticks for them. DasAxis clients should offer their ticks to this master, which will decide which set of ticks to use.
offer a set of ticks. This can be called from off or on the event thread, but a new thread is started so the task is performed off the event thread.
kludgy solution to problems where an axis didn't get the update from its parent. This is only called as a last-ditch measure.