Added secondary source selection and driving function for 3D WFS
Kaiser tapering window and computation of 3D sound field (or plane)
Various changes
Added plane wave as source model
Added line source
Added line source and plane wave as source types
Merge branch 'non-linear-arrays' of https://github.com/sfstoolbox/sfs-python into non-linear-arrays

Conflicts:
	sfs/source.py
Changed calculation of plane wave and added default arguments
Added inner product again
Merge branch 'non-linear-arrays' of https://github.com/sfstoolbox/sfs-python into non-linear-arrays

Conflicts:
	sfs/source.py
Added indication dtype=object to an array