Release version 0.5.1

New minor release, adding the following features and fixing the following bugs:

Added

• Better support for FBP:
  • Dedicated solver class.
  • Support for 3D geometries.
  • Use of scikit-image's filters, with rfft.
  • Support for various padding modes (constant, edge, etc).
• Support for various padding modes in gradient, Laplacian and convolution operators.
• Support for Lorentzian and sech^2 beam shapes.
• Computation of Center-of-Mass for volume.

Fixed

• Border behavior in convolution operator.
• Sanitized projector's angle input.
• Denoising / deconvolution method.
• Models: handling of astra-toolbox's 2D rotation direction.