* Add initial Ellipse Tool to the Editor Mode. Currently there's
something wrong with the algorithm and the ellipses have a sort of
'lemon shape' to them.
* Refactor the IterLine/IterLine2 functions to be more consistent.
IterLine used to be the raw algorithm that took a bunch of coordinate
numbers and IterLine2 took two render.Point's and was the main one
used throughout the app. Now, IterLine takes the two Points and the
raw algorithm function removed.
* Fix the EditorUI not showing the correct palette baked into the level
and only showing the default. This was tricky because the palette UI
can only be configured at setup time but not updated later.
* Add a new default palette for the Blueprint theme. Blueprint has a
dark background, so the palette colors should be bright. This palette
is chosen when you start a map with the blueprint wallpaper.
* Add a background Canvas to the MenuScene. In the "New Level" screen,
the background canvas will update to show the wallpaper settings
you've chosen as a preview of the level theme you're about to create.