* The game's tick counter was moved from Doodle.ticks to shmem.Tick
where it is more easily available from every corner of the code.
* Fix a bug in the Level Editor where dragging an already-existing actor
from one part of your map to another, would cause it to lose all its
data (especially its UUID), breaking links to other doodads. Now the
existing Actor catches a ride on the drag object to be reinserted
later.
* Animate the Link Line visualizers between actors. They now animate a
blinking color between magenta and grey-ish.
* Toolbar has icon buttons for the Pencil Tool, Line Tool, Rect Tool,
Actor Tool and Link Tool.
* Remove the tab buttons from the top of the Palette window. The palette
tab is now toggled between Swatches and Doodads by the tool selected
on the tool bar, instead of the tab buttons setting the tool.
* Remove the "Link Doodads" button from the Doodad Palette. The Link
Tool has its own dedicated toolbar button with the others.
