Implemented Layouts

Vertical ( default ): vertical stack of panels;
all time panels are of the same width;
one XY panel in the line;
generic panel height (for Time and XY panel)
and width (for XY panel) can be defined at this level

Auto : automatic layout - if possible combines
several XY panels at the same level; only panel height can be defined (XY panel is 'square')

Manual : everything is to be defined by user

Two generic panel types : 'Time/Epoch' and 'XY (Scatter/Instant)';