BaseGraph coloring support

This release brings support to assign actual colors to vertices of the basegraph based on coloring vertices and meta coloring vertices.

Additions to library

Visualization library involves modular methods to assign coloring using a color dictionary and lambda functions that accept a vertex and assign it a color.
The library also includes various helper functions and support to play with colors of the BaseGraph, such as with the get_vertex_color and get_possible_colors methods.

Additions to the GUI

The GUI implements ability to click on a vertex of a ColoringGraph, MetaGraph or Partial ColoringGraph and color vertices of the BaseGraph the corresponding colors. Since MetaVertex objects can be composed of many coloring vertices, the 'locked' vertices with fixed colors will be colored with their assigned fixed color, whereas 'unlocked' vertices with uncertain color will be indicated differently.
Additionally the GUI supports clicking on edges to see what vertex/vertices change(s) colors through that edge. In case of ColoringGraph or Partial ColoringGraph, and edge corresponds to the change in the color of exactly one vertex, whereas in a MetaGraph this may be any number of vertices.
Further enhancements include, ability to load/save from/to a file on the disk in adjacency matrix format.

Various bugfixes.
#7 #9 #5 #8 #6

0.0.3.post1: web app

stable working version of webapp and other improvements to library.

• open graph and view its coloring and metacoloring graphs in the same view
• edit basegraph and regenerate cg, mcg
• start from scratch and draw own graph
• stable layout with placeholder for upcoming feature: partial coloring graph 'pcg'

0.0.2.post2

release with functioning basic implementation, Tarjan's code, and a CLI entrypoint to plotting from anywhere