Improvements and bug fixes

This release contains bug fixes and minor improvements. Please update to the latest version. See changes.txt for detailed changes in this release.

Updates in v0.8.1
TYPES:

1. Types.CorrData.subset: clarified documentary of overwrite option. Default False.
2. Added a new class for plotting shaded relief based on cartopy.

NOISE:

1. In shaping_corrdata(), modified to loop through all pairs and all components, if not specified by the user.

UTILS:

1. qml2list:add option to only extract location and dates.
2. slicing_trace(): fixed a bug when all trace std was computed using the amplitudes instead of the absolute amplitudes.
3. slicing_trace(): changed to compute trace_stdS after demean and detrend.
   added demean and detrend of whole trace at the beginning.
4. import tukey from scipy.signal.windows to be compatible with different scipy version.

DOWNLOADERS:

1. get_events(): added depth range and search with radius in circles.

PLOTTINGS:

1. plot_stations: added options to specific colors and renamed it to gmt_scatters() to be more general.
   Old function was kept but will throw an error.

OBSMASTER:

1. import tukey from scipy.signal.windows to be compatible with different scipy version.