2.0.0-beta.7: 1d Confidence Regions (#145)

* 1D confidence regions function added to utils and optional plot added to fastkde_plot_1d

* generalisation of iso_probability_1d function to handle different contour values and changes to related plot functions

* testing of iso_probability_1d via plot functions

* double checking and editing docs

* flake8 compliant and increased coverage

* added explicit tests to for utils 1d propability contour function

* flake8 on test_utils.py

* changed color kwargs to use pre-existing, fixed docs and moved fill_between plotting into "helper" function

* flake8 fix

* docstring fix in fill_plot_1d

* docstring fix in fill_plot_1d

* adapting 1d contour method to properly plot intervals using existing utils functions

* removed redundant iso_probability_1d function

* updated test_utils.py to meet changes with the code

* minor change to fill colors

* changed color scheme to match up with 2D posterior plotting

* updating tests to fit with change in code

* added back in cmap kwarg, seems to crash tests without it

* flake8 fix

* added filledkde and filledfaskde plot types

* fixed tests

* added new samples tests for the additional code

* removing filledfastkde test in samples as fastkde doesnt appear to be in requirements

* trying to get codecov/path to pass

* fix for fastkde 1d filled plots

* adding in weights for iso_probability_contours_from_samples call

* fixed issue when changing colormaps

* fixing flake issue

* triggering fill with facecolor for 1d plots and removing filled1d kwarg

* reorganised kwargs for filled 1d plots/color scheme

* edits to color scheme

* few edits to plot.py and additional tests added

* bumping beta version number and fixing docstring error