Colomoto-jupyter

Improvements in `colomoto.minibn`:
* `BooleanNetwork.simplify()` apply stronger simplifications for DNFs
* add `MultiValuedNetwork.simplify()` method

colomoto_jupyter`:
* `tabulate` function now uses pandas and sorting for pretty display

`colomoto.minibn`:
* add `sanitize_names()` and `rename()` methods
* load accepts remote files

* fix compatibility with recent IPython versions

Added:
* `colomoto.helpers.layout_graph`: returns layout of a networkx graph using GraphViz
* rough `influence_graph()` for `colomoto.minibn.MultiValuedNetwork`

new methods for `minibn.BooleanNetwork` :
* `__call__(x)`: returns `f(x)`
* `constants()`: returns a mapping between constant nodes and their constant value.