Improve SVG TS viewer

DONE * make lines in SVG TimeSeries Viewer thiner when zoom in

CAN NOT REPRODUCE * With the TS in the attachment, SVG viewer displays all the lines crowded in the top area. This should not happen, and a nicer spreading should be computed

DONE * From Tim and Viktor:

• When we zoom, the normalization in amplitude could be recalculated in order the fill the empty space, and thus see better the time series.
• That is true, we do not have a normalisation in amplitude, we just plot values as they are, regardless if they are zoomed or not. I will make this a strong priority.
• Maybe then a even easier way that normalization is just to increase the space in the plot on which the values are spanned when zooming. I attached zooms in maplotlib for demo

WILL NOT BE DONE * make lines colored as in Matlab ?

Some more suggestions from MW (TVB-1014):

• Add horizontal grid lines for the zero of each channel and vertical grid lines for each time stamp shown along the bottom.
• Fix the SVG scaling in the whole visualizer, so that lines do not expand in area, essentially reducing the fidelity of the line when only a few signals are shown, as small variations cannot be seen
• Fix and provide options for the temporal context (bottom window) which does not appear to always work correctly, and should be configurable for other metrics (like synchronization, etc.)