Make vertex labels in graph visualization start at 1

[YueRen]

See title. Also, @ollieclarke8787 and I would make it so that the user is allowed to specify vertex labels, is there already an agreed upon syntax for that?

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 84.39%. Comparing base (a60b0d8) to head (cbb6db1).
Report is 59 commits behind head on master.

Files with missing lines	Patch %	Lines
src/PolyhedralGeometry/visualization.jl	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4459      +/-   ##
==========================================
- Coverage   84.42%   84.39%   -0.03%     
==========================================
  Files         668      668              
  Lines       88363    88609     +246     
==========================================
+ Hits        74600    74785     +185     
- Misses      13763    13824      +61     

Files with missing lines	Coverage Δ
src/Combinatorics/Graphs/functions.jl	96.71% <ø> (-0.02%)	⬇️
src/PolyhedralGeometry/visualization.jl	44.11% <83.33%> (+6.18%)	⬆️

... and 16 files with indirect coverage changes

[benlorenz]

I pushed a commit which integrates the graph visualization with the generic one, this allows setting labels with a keyword argument:

julia> visualize(g; VertexLabels=["a","b","c"])

And by default it will use 1..n.

This also allows visualizing multiple graphs at once.

[YueRen]

@ollieclarke8787 and I also tried it out on the large examples we care about and we can confirm that it works like a charm.