Modified the PointCloud object to create a separate point list using arbitrary columns instead of the 1st three columns.

Additionally, PointCloud can generate 2-D and 1-D point clouds as well (implicit 0's along the missing dimensions.)
Added ability to switch between a point cloud, cube or ico sphere cloud.  Only points work ATM.
Fixed bug with populating cubes and icospheres.  All are tested.

NB, the settings for selecting a pointcloud or object and which columns in
the csv file are X, Y and Z are still set in the code.  Adding a UI next.
Updated the ver number for the addon.