v0.5.0

• sep.extract() now uses a more correct matched filter algorithm in the
  presence of a noise array, rather than simple convolution. The conv
  keyword has been changed to filter_kernel to reflect this, and a
  filter_type keyword has been added to allow selecting the old behavior
  of simple convolution.
• sep.extract() now accepts a mask keyword argument.
• sep.extract() can now return a segmentation map.
• Special methods added to allow data - bkg and np.array(bkg) where
  bkg is a Background object.