csb.io.plotting.Chart:   - changed the signature of the constructor: added rows and columns parameters   - added accessor for the first (default) plot in the collection
csb.io.plotting.Chart:
  - changed the signature of the constructor: added rows and columns parameters
  - added accessor for the first (default) plot in the collection

csb.io.plotting.PlotsCollection  :
 - access plots by index or by (row, column) tuple
 - removed the add() method; plots are now added automatically

csb-toolbox/CSB