baseapp: Should routes allow numbers

[ValarDragon]

Ref #1579 (comment)

Previously we had an error saying they were alphanumeric, but were actually only allowing alphabetic. The error has been changed to reflect that the routes should be alphabetic. However, I think we should allow numerics in routes. Conceivably, a module could want several similarly named modules / several modules with slight alterations running together, and numerics are a convenient way to do this.

I don't see any downside from adding numbers, other than possible 1, l and O, 0 ambiguity.

[rigelrozanski]

Yeah I agree - I don't see the problem

[AdityaSripal]

Could we also allow backlashes? Would be nice to namespace message types by module.

Ex: bank/send

[ValarDragon]

That ties into #770

I prefer we don't allow that now. I would rather not have peoples routes silently break in a future sdk upgrade.