Uncommented a bandpass
Fixed the time handling of the imp driving functions

The time conversion of the driving functions is implemented and the time vector t is fixed in order to work with this.
Added missing stuff for last commit
Changed the bandpass handling. Now a config option exists
Fixed invoking bandpass by adding conf input parameter
Added a option to specify the greens function directly for the wave_field_mono function
Changed point_source etc. to point_source_mono etc.
Updated all functions to use the new point_source_mono etc. functions
Cleaned up the usage of conf.phase in the driving functions