Re-work of creation path

Start of work to make entity creation path easier. Needs to support both
create a new object on click and create new object from clipboard.
Bug fix for spline rendering.
Added EntityEditInfo

Broke out properties about what edits can be applied to an entity into a
separate class. Done so I don't have to keep adding interface properties
each time I add something new.
Spline settings

- Spline settings
- Added a default Size2D to the settings default value attribute.
Settings system ReSharper cleanup.
Common ReSharper cleanup.
TODO update.
Remove collision handling from group.
Changed smart manipulator keys to make more sense.

X limits to X
C limits to Y
Close spline by default.