Patterpad 0.16.0

Changed

• A condition comparing flags no longer depends on the order they were added. @f == [red, blue]
  now matches a value built as +blue then +red, and every Patterplay runtime agrees with the editor
  about it. A flags value is a set; its stored order was an artefact of the order somebody happened to
  write the outcomes in, which nothing in Patterpad ever showed you. A condition that was quietly false
  for that reason will start passing, which is the answer it should always have given.

• Saves your game writes can be read by the Unity, Unreal and Godot runtimes. The random-number
  state was recorded as a signed number, so more than half of all saves carried a value the native
  runtimes rejected: Unity threw on load and the C++ one read it through undefined behaviour. Patterpad
  and the JS runtime always coped, so this never showed up here, which is exactly why it lasted. Saves
  written before this release still load everywhere.

• Under the hood, the expression language and the shared authoring pieces come from @wildwinter/expr
  and @wildwinter/toolkit rather than copies kept here. One implementation, shared with the Storylet
  Engine, so a fix lands once instead of twice.