update waveform plot

This MR updates the waveform posterior plotting method to make it more clear.

I've attached the new version of the plot for GW151226.

added Plotting/Visualisation + 1 deleted label

changed the description

Hello, I think there is a bug in the asd_from_freq_series() function in Bilby:

According to the equation of optimal SNR:

the asd_from_freq_series() should be

I will make a merge request very soon.

mentioned in merge request !770 (closed)

mentioned in merge request !771 (closed)

approved this merge request

approved this merge request

merged

mentioned in commit 93f712c4

changed milestone to %0.6.8