Replaced k by omega in functions calls, speed of sound as optional argument, order of arguments in synthesized.generic
Added argument to allow selection of secondary source type
Added driving function for 2D WFS Linesource
Changed handling of wavenumber
Merge branch 'k->omega' into 2d

Conflicts:
	sfs/mono/drivingfunction.py
	sfs/mono/synthesized.py
Changed handling of secondary source type, renamed driving functions
PEP8 compliance
Code restructuring