Time Strip swimlane height and label column width should be user settable

[charlesh88]

Is your feature request related to a problem? Please describe.
Allow Time Strip label column width and swimlane heights to be set by the user.

Describe the solution you'd like
Include a UI control when editing a Time Strip that lets the user set desired width of the label column and height of each swimlane. The example below shows a possible design solution utilizing draggable edge controls, similar to how Flexible Layout editing works.

This is needed for Events and Commands in Time Strips enhancement.

[charlesh88]

Digging into this a bit, I recommend the following:

• We should consider storing all user-set widths and heights as percentages instead of pixels. This would allow a pivot into flex-height Time Strips, which would be advantageous. We could still do fixed-height TS's (if desired) by simply setting an explicit height on the overall c-timeline-holder container. Flex-height TS's might require the user to be able to set a minimum px height on each swimlane though.
• We should convert the TS layout approach to use a single grid at the highest level, on c-timeline-holder.
  • Punting on this idea. The markup makes this impractical, we'd have to use even more display:contents assignation to make it work.

[charlesh88]

Just pushed changes to 7957-adjustable branch.

• timeline-holder now set to 100% height.
• c-swimlane now space-fills available vertical space, and provides overflow scroll.
• Screenshot below shows where user-defined heights should be set.
• Smoke tested in Plan and Gantt views and works as expected.