Description of proposed changes

This PR adds a function to read GMT lon/lat file so that one can plot the faults dataset (created by GMT from KML file) on top of the view.py plot, in Python level ONLY.

• add utils.plot.read_gmt_lonlat_file() to read and plot faults on top of view.plot_slice() output

  • add notes and examples on how to prepare the GMT lonlat file from KML file, and use the function in python

• objects/gps:

  • add horz angle to the filename if it's horz and print out file name before the long calc
  • print warning instead of raise error if no GPS found
  • more print out num while comparing with GPS

• tsview: support TS file w/o REF_Y/X

• legacy/2to3_timeseries: change P_BASELINE_TIMESERIES to optional

Reminders

• Pass Codacy code review (green)
• Pass Circle CI / local test (green)
• Make sure that your code follows our style. Use the other functions/files as a basis.
• If modifying functionality, describe changes to function behavior and arguments in a comment below the function declaration.
• If adding new functionality, add a detailed description to the documentation and/or an example.