Fix for #1579
Added import statements to run examples individually
Fixed 2D and 3D convolution 'None' mode
Changed default of convolve to 'fill'
Canged import order and removed blank lines
Removed redundant complex type check
Added masked array and normalize function tests
Added boundary=None for list test
Fixed masked array handling in convolve_fft
Changed docs to new default behaviour
Add .cgs and .si convenience properties to Unit, to be in line with Quantity.  Fix #1610
Fix for unnessary path elemnts in timer docstring

[ci skip]
Fix table masking and filling example
Merge pull request #1626 from taldcroft/table/mask-docs

Masking example broken in table docs
Fix rst doctests in top-level docs
Fix rst doctests in wcs package
Fix rst doctests in coordinates package
Fix .rst doctests in convolution package
Fix .rst doctests in constants package
Fix .rst doctests in config package