Add possibility for custom cmap in SpectrumSeries, SpectrumSeriesPlot, Plot1DMultiLineSingleAxis, Plot1DSingleAxis, Plot1D

Desired features:

• selectable cbar
• selectable norm
  • list of cbar positions?
  • cbar position property for existing classes?

Changes needed:

• SpectrumSeries
• SpectrumSeriesPlot
• Plot1DMultiLineSingleAxis
• Plot1DSingleAxis
• Plot1D

templist = []
    
for key in keys:
  templist.append(int(key[:3]))

tmax = max(templist)
tmin = min(templist)

# set colormap cool
cmap = plt.get_cmap('cool')  

# set norm function to norm excitation power for colorbar
norm = Normalize(vmin=tmin, vmax=tmax)

for i,key in enumerate(keys.values):
  self.addLine(data.values[i], key, c=cmap(norm(float(key[:3]))))