Fixing typos and links

Added geometry to the Ugly Tie polygon to look like a knot. 

It remains a single polygon so color will affect both visible parts. 

At large zooms/resolutions a connection between the right side of the knot and the main tie is visible because the points on right side of the knot are not perfectly in-line with the upper right corner of the tie where the two larger parts of the shape are visible. If this becomes an issue, doing some math to find evenly dividing, aligned points near the current values would make the connecting section of the polygon zero width.

repeated first point in 5th position to close knot shape. Added `np.nan` non-rending connection point.

Add knot to Ugly Tie shape

  - /mpl-data/sample_data/axes_grid folder appears to no longer exists as of matplotlib v2.2.2
  - added /assets folder in repo containing dependent numpy pickle, 'bivariate_normal.npy' file
  - revised load of data in AnatomyOfMatplotlib-Part2-Plotting_Methods_Overview.ipynb to reflect this change
  - tested successfully with matplotlib v2.2.2 and python v3.6.6

  - removed redundant cell (typo on my part), line 272

Fixes #26

Before the changes, the table was not rendered properly.

Fix markers table for display in JupyterLab

Add explanation for imshow usage

…n warning

Updated `bar.set(color='salmon', edgecolor='darkred', linewidth=3)` to pass `color` before `edgecolor` to fix `MatplotlibDeprecationWarning`

Updated with changes as per newer matplotlib api to remove deprecation warning