[Scenario] Timeline Rollout #1 Features

Features for timeline rollout 1 are provided in this pull request.
Primarily, these changes are the refactoring/decomposition of 
existing components (to expose behavior through Capabilities) 
and views (into smaller views, to support things like selection).
Additional user interface features have been added, such as 
constraint enforcement for sibling activities and pan/zoom 
controls for Timeline views. Some unused code has been 
pruned.

Issues addressed are:

#7 
#10 
#11 
#14
#15
#17
#18
#19

Partial support for #9 and #21