Add support for escaping the backquote in vertex statements

[CrazyPython]

trafficstars

This should be permitted:

a -> b
a = `\``

[r2d4]

Agreed. Maybe we should adopt the Go syntax with "" for interpreted strings and `` for raw string literals

[CrazyPython]

"" would be great.

Also, can you point me to where you implement Topological Sort in your Go implementation? I'm almost done with my JS implementation, it just needs TopoSort.

[r2d4]

https://github.com/r2d4/virgo/blob/default/pkg/virgo/topsort.go