Fixed bug in Points.roi property when the ROI is not set
Fixed bug in Points.resize method
Points and PointPlot now support points with magnitude (colored by cmap)
Improved support of Nx3 arrays in Points constructor
Bug fixes and improvements in clarity
Generalized the constructor of Points, removing 'magnitudes' argument

This constructor is both simpler and more flexible. Furthermore, exactly
the same constructor can be used for VectorFields.
Introduced VectorField as a subclass of Points
Initial commit of VectorFieldPlot with incomplete update_frame method
Enabled animating colors and angles on Quiver plots