Add support for automatic module name

[dmlloyd]

Fixes #520 for the 3.x branch.

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[elharo]

remove log messages

[elharo]

I don't think this should have log messages. Having a module descriptor should not cause a warning.

[desruisseaux]

I understand this warning as being not about the presence of a module descriptor, but rather about the present of an automatic module name in a context where it should not be present.

Note: this set of changes is the same as #521, only applied to different branches. Comments here apply also to #521.

[dmlloyd]

Having a module descriptor does not cause a warning; having a module descriptor which conflicts with a defined automatic module name should cause a warning.