Add a way to set arbitrary language names

[Antoine Pietri]

Using __class__.__name__ is a cool default but I think we should give more control to the user (like using a name descriptor that gives __class__.__name__ when not set).

[Alexandre Macabies]

What do you think of:

class Python(Lang, name="my-python"):
    pass

[Antoine Pietri]

sgtm

[Alexandre Macabies]

models: add name= kwarg on Lang; fix #12

→ <<cset 5e0aed803b42>>