Allow mypy to be run against a directory recursively

[kylec1]

It'd be useful to be able to run mypy on a whole project (or a subset of one) by just pointing it at a directory, and that can probably be done more efficiently than checking each module or file individually, as type information from dependencies could be shared.

[JukkaL]

Yeah, this would be pretty useful.

[o11c]

On my driver branch you can badly work around this with mypy -c 'import foo, foo.bar, foo.baz' (listing all). It shouldn't be hard to add a new flag that generates a -c.

But (and this is critical) note that this will allow certain import-order-related bugs to go undiagnosed. Mypy had several bugs in this regard, this why my driver PR typechecks each module individually.

[alunduil]

Is this being deprecated in favour of #935 ?

[JukkaL]

#935 covers a superset of this issue, so this is no longer relevant. We may still support running against a whole directory, but we've discussed that in the context of #935.

[gvanrossum]

(The fix for #935 also adds support for this.)