apply @holiman s graph changes +

add demod data to graph.
some bugs are known:
if you close the graph window data plot will not bring it back.
exiting the application without closing the widget form results in
error.
autocorrect graph y labels are ugly
form has old askdemod tab.
sticky button purpose not defined/labeled well.
doesn't clear s_Buff when new graph loaded or sampled.
probably more...