We need custom validators from go command line validation

[tjayrush]

See this issue: spf13/cobra#745.

We would like to use this method (composing validators) in our auto-generated code, but we need some more custom validators. Four immediate validators would be:

• IsValidAddress
  • 42 characters long
  • starts with 0x
  • hexidecimal
• IsValidHash
  • 66 characters long
  • starts with 0x
  • hexidecimal
• IsValidBlockIdentifier
  • uint64
  • IsValidHash
  • named block
• IsValidTransactionIdentifier
  • .uint64
  • IsValidHash
  • named block.uint64
  • .*

Do not call into the RPC for any of this first level validation. The called-into routines can do deeper validation (i.e. is this even a valid block?) when they're called because they must use RPC anyway to fulfill the request.

[tjayrush]

We're well on our way with the new block range parsing. This will happen naturally.