Add other axes limits rescaling options #54
Description
Currently the axes limits are not automatically adapted when a mode is added or removed from the plot. This is good, because we don't want the limits to change continuously. If there are modes which exceed the axes limits, it is possible to change the limits by a button which uses the automatic matplotlib scaling, or by manually adapting the limits through the matplotlib toolbar. The first option is useful, but often zooms in too much. The second option is also useful in some specific cases, but not practical in most cases.
It would be good to have additional options like 'rescale limits, but keep lower frequency limit at 0 and lower damping limit at -1%' (or something like that)