more fixes for ipywidgets usage

For example replaces .width with .svg_width to prevent naming collisions.

Compatibility with ipywidgets 5.1.4

Update to work with latest dependancies. Includes pull request omitted in 1.1.

Compatibility with ipywidgets 5.1.4 (obsolete)

This point release allows jp_svg_canvas to work with the latest version of ipywidgets at this writing. Note: this release was in error -- the pull request for the changes had not been merged :(.

Before fixing issue with ipywidgets upgrade

This version worked with the old version of ipywidgets.