Fulcrum v4.3.0

Release notes

One thing runs through this release. The gentle self-reading behaviour the
help dialogs already had now reaches every explanatory surface that can
overflow, so no part of the family is left half in it.

Experience

• A signal's definition reads itself. The dialog behind a signal's
  magnifier button explains what the reading measures, its unit, when it
  reads high and what it maps to. On a short window, or with a longer
  definition, the tail of that sat below the fold and had to be found by
  hand. It now holds still on open, reads itself down at the same pace as
  the glossary and the licence texts, holds at the end and rewinds. Nothing
  changes for a definition that already fits: the cycle moves only when the
  content actually overflows, so attaching it to a surface that currently
  fits costs nothing.

• The guide's move list reads itself. A frame's line can run to more
  moves than the pane shows, exactly as the board's own move list can, and
  the board's list has read itself down for some time while the guide's did
  not. The two now behave identically. Scrolling by hand, dragging the
  scrollbar or tabbing onto a move row suspends the cycle, and it picks up
  from wherever you left it, so taking over never switches the behaviour off
  for the rest of the dialog's life.

Both surfaces run on the shared constants rather than their own, which is
the point of doing it this way: one reading pace for the whole application,
so no dialog can drift into feeling faster or slower than its neighbours.