Slashes are not escaped in paths

[Oriol Brufau]

1. Run inspect({a: {b: {}}, "a/b": []})
2. Expand a
3. Expand b (inside a)

Result: a/b is also expanded.

Either escape slashes in paths, or consider using symbols instead of strings to avoid collisions.

[Nicolas Chevobbe]

Node paths were refactored to use Symbols in #1013 , so we don't have path clashes anymore