Suborigin names should not be allowed to start with number

[joelweinberger]

At the very least, suborigin names should not be allowed to be a pure number, as in the serialization this could easily lead to parsing bugs that confuse the suborigin name with an IP literal. It's probably sufficient to just ban starting with a number, although perhaps we should outright disallow numerals.

[annevk]

Maybe we should instead figure out what is absolutely safe in all the various contexts and use that? E.g., lowercase a-z?

[devd]

I like the lowercase a-z idea. It also gives us ability to namespace later via upper case / numbers (for #40 )

[ghost]

a-z would break our current usage of suborigin in IPFS, where we use multihashes as suborigin names to isolate e.g. /ipfs/Qmfoo from /ipfs/Qmbar. I suppose we could encode the hashes with a-z only, but that's less ideal than base32.

It's probably sufficient to just ban starting with a number, although perhaps we should outright disallow numerals.

Both of these would work for go-ipfs :+1:

[devd]

closed per above merge