Suggest checksum words when simply entering seed.

Right now the only way to get the checksum word tool has to be used to derive the last word option.

This is useful for people using plain sight seed, Arbitraty text transposed to BIP39. (Similar to a brain wallet)

The standard way to use this scheme is that the fist possible valid word is the last word.

Right now the seed has to be entered twice to get to know the last word AND use the wallet.