Pathmodel

Fix

* Issue with installation by adding a `setup.cfg` file.

Add

* new argument `step_limit` (`-s` in command line): this argument is used to avoid endless run of PathModel. Indeed, in previous version if the goal molecules could not be reached, the tool continue its prediction trying to reach them. Now, PathModel has a minimal number of step in which the goal molecules must be reached (by default it is 100 steps). The number of step can be modified with this new argument.
* `__version__` to pathmodel.
* Mozukulin and Brown alga sterol pathways data.
* `CompareMolecules.lp` to compare molecules and check transformations from known reactions.

Fix

* Issue with atom numbering in `pathmodel_plot`.

Add:

- tutorial to reproduce article experience.
- predictatom and predictbond to represent inferred molecules from M/Z ratio in pathmodel_output.lp.
- better pathway picture (only blue square for inferred metabolite from M/Z ratio, remove absent molecules).

Fix:

- missing reactions in MAA pathway ('sedoheptulose-7-phosphate' and 'R-demethyl-4-deoxygadusol').