When the settings change, the depth axis is redrawn
to reflect metric/imperial units. To check whether the
units changed, the old length unit is saved in a static
variable. This makes no sense and allows for only one
depth axis. Make this a normal member variable that is
initialized in the constructor.
Also remove the settingsChanged() call in the constructor,
since this is a no-op (the depth unit is unchanged).
Contains a whitespace fix.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
e61466e178