disallow numbers in the dpath

[nmushegian]

It will be abused like :pack:coin:v2.0

[chaserene]

what do you think about limiting numbers to a single, terminating digit throughout the whole dpath? :pack:coin:v2

I see your abuse scenario, but numbers will be needed for release versioning. we ran into this during the hackathon when trying to register :free:weth9 in dmapper (wanted to showcase the value locking feature).