new options in waveform:
linestyle
grid_color
grid_linewidth
grid_linestyle

remove the linewidth in the _plotEvent

documentation in stream updated
":param data_unit:" documentation corrected
pep8 style correction in  waveform.py
Revert "pep8 style correction in  waveform.py"

This reverts commit 35a523917eb9019309c28396818c4b904042c947.
pep8 style correction in waveform.py
Merge pull request #545 from bonaime/waveform_enhancement

Waveform enhancement