Fixes and enhancement for cx2 integration with networkx and pandas

• Enhancements

  • Added store_layout_in_pos argument in get_graph method of CX2NetworkXFactory that saves layout
    coordinates in G.pos (x and y) and G.zpos (z).
  • Added get_layout_from_pos argument in get_cx2network method of NetworkXToCX2NetworkFactory that
    determines the source of the layout coordinates. If True, the layout is derived from G.pos (x and y) and G.zpos.
    If False, the layout uses the (x, y, z) values specified as the node attributes.
  • Added interaction_col argument in get_cx2network of PandasDataFrameToCX2NetworkFactory that allows to
    specify the name of the column with edge interactions

• Bug fixes

  • Fix for string IDs in NetworkX networks - cast to integer if possible or add as name attribute.
  • Fix for DataFrames without column names