Added blocking dialog box 'TimelineProgressDialog' that comes up when
timeline processing begins and closes when it is finished. This is to
prevent users from starting another timeline processing job while one is
already underway.
Added code to prevent selection of 'Make Timeline' (from Tools menu) from
running timeline again and opening additional windows.
Added JSplitPane to timeline window to separate the barchar area on the top
from the viewers on the bottom.