This change automatically changes the view direction to look
at a <marker> if any is defined for a checklist item or tutorial
step.
Both the tutorial and checklist features support a <marker> element
which can be used by an aircraft developer to display a magenta
circle around an item of interest (typically a control in the
cockpit).
Previously aircraft developers had to add a <view> element to move
the viewpoint to look at the marker, while users of checklists had
to look for the marker manually.
Now:
- For checklists, pressing the "?" button on a checklist will pan the viewpoint
to the marker.
- For tutorials, if there is not a <view> element defined for a
tutorial step, the view will automatically pan to the marker.
<message> tags can now contain sprintf() format
strings (%d, %.2f etc), with
<message-param>
<property>/some/prop</property>
</message-param>
used as the substitute value. Could be extended
in the future with perhaps Nasal evaluation?
When user switched to a different view mode (e.g. chase/helicopter/tower
view) before or during a tutorial, everything went wrong...
Need to control (save/restore/switch) the view number (view mode) during
tutorials. Also adds an option to explicitly change view mode during
a tutorial, i.e. tutorials can switch to tower view, chase view, ... now.
