Changes:
* Clicking and dragging with MMB pans the screen (except while placing objects).
* The menu animation speed can be increased in Settings.
* Compound regions can be selected by holding shift with a region selected and dragging to add a region.
* Undo/redo interacts sensibly with cut/paste.
* Added a "Duplicate with Wires" action (can be bound in Settings)
* Key bindings can now include the modifier keys Shift and Ctrl, if desired.
* Allowed save selection menu to span multiple pages when necessary.
* Fixed the background generation for larger levels, keeping proper parallax effect.
* Various improvements to the Lua API:
* ...Added are .step_count and .step_time properties in CollectorHandle
* ...Added a new class "ElectricStatus" which accurately tracks the state of pistons and such.
* ...Added a new class "MouseInfo" for state:on_interface_update callbacks
* ...Added game:track(...) which allows Lua to track an object.
* ...setup_utility.lua allows achieve_main to be a table and has the new user_block_indices key
* ...Added .input_extra and .output_extra properties to the CreatePortal interaction.
* ...Added :neighbor and :meeting methods to physics side.
* ...Resizing the top portion of the map now works properly.