v0.13.4

Changes

• Fixed an NSRangeException raised from a layout pass. A scroll in the middle of an edit (undo and
  paste select and scroll to the result) could start a pass after the text storage had changed and
  before the line storage had caught up, and typesetting a line from its stale range read past the end
  of the text. layoutLines now waits, and marks layout dirty, while the two lengths differ. An
  exception raised there had left the layout lock held, which skipped every later layout pass in 0.13.1
  and hung the main thread before that.
• Removed the Objective-C exception catch added in 0.13.3. Catching an exception that has unwound
  through Swift frames skips their cleanup, and the app crashed in swift_beginAccess shortly after one.