Update reference to 'amp' & 'amplitude' -> 'height' or 'power'

[TomDonoghue]

Responds to #131

Notable changes (in code):

• Public setting min_peak_amplitude -> min_peak_height
• Private setting _ap_amp_thresh -> _ap_percentile_thresh
• Reference to 'Amp' as a usable label to select data -> 'PW' (for power)

Notable changes (in documentation / tutorials):

• Where possible, most references to 'amplitude' things have been made agnostic, referring to 'height' instead of using the words 'amplitude' or 'power'.
• Where in reference to extracted peaks in particular, the word 'power', with abbreviation 'PW' is used.
  This is in context of labelling peaks as {'CF': center frequency, 'PW': power, 'BW': bandwidth}
• Through doing this, I noticed some inconsistencies of when things are referred to as 'peaks' vs 'gaussians', so some updates (in documentation / description) related to that as well.

Open Question:

• I'm not super convinced about using 'PW' for 'power'. It has a nice symmetry of indexing using 'CF', 'PW' and 'BW'. Most likely alternative is probably 'POW'.
  • ^This should be a pretty clean find & replace to update / change, if anyone has suggestions / votes on a change to this.

[voytek]

just one comment

[voytek]

PW is fine. Don't overthink it too much.