VI Chart updates

Just a quick note to say that I have just committed to master some changes that will break the VI-Chart node in existing files, and you will need to recreate any chart nodes in your node tree. It may also be necessary to recreate some simulation results in order to be able to chart them. If charting climate data you just need to re-select the EPW file in the VI Location node.  LiVi CBDM and EnVi analyses will need to be re-simulated. Other simulations should be OK.

Sorry for any inconvenience but the implementation is now much simpler and easier to maintain.