0.4.0

• performance improvement for Interp2D (Interp2D::index_point() is now much faster) -50% for most interpolation methods
• runtime specialization for interp_array methods when query dimension is Ix1 ~-20% improvement
• add interp_into() and interp_array_into() methods for interpolating into a user provided ArrayViewMut
  this can improve performance by avoiding memory allocations.
• fix crash when IxDyn dimensions are involved.