parts re-render on self-initiated changes

[YairMarcowMavenomics]

The framework seems to unnecessarily call render on Parts when they change their own Properties, resulting (most obviously) in visible overlays, for example when a SlickGrid column is resized, and potentially in lost state (e.g scroll position), stickiness etc.

Things to consider:

• Existing Parts could potentially depend on applying their own changes to themselves via render.
• Other potential cross-cutting future API changes such as removing explicit initialize, adding onOptionsChanged.

[quigleyj-mavenomics]

Tasks:

• Review Parts and UDPs
  • Various UDPs, and possibly a built-in part or three, rely on this behavior.
• Review SlickGrid
  • This needs careful study- the grid shouldn't be relying on this, but might be as a matter of course.
  • Review the PnL, Fund Summary, Rocket Motors, and Table Editor demos for correctness
• Review docs
  • The existing inline part docs would still be mostly correct, they just need a few tweaks
  • We don't have other public docs on part writing, so no updates needed there
• Extend the OptionsBag to allow "external" writes
  • Needed for eg, Part Properties editor, PartManager unit tests.
• Update PartManager unit tests
  • Remove places where we test for old behavior
  • Ensure that we test this new behavior

[quigleyj-mavenomics]

Plan is to push this to a branch first to test for any real-world failures, then slowly move UDPs away from this behavior. The process of doing that should help us uncover any major spec risks that we haven't yet seen in making this change.