Vyper decimal10 abi type support

[djrtwo]

• Version: 4.0.0-beta
• Python: 2.7/3.4/3.5
• OS: osx/linux/win

What was wrong?

There is currently no support for vyper abi type decimal10. Although vyper is in alpha, it is increasingly used by ethereum research team for casper and sharding.

How can it be fixed?

Add support for decimal10 abi type :)

[djrtwo]

This is on my to-do list but I'm not sure when I will get to it.
If someone else begins development on it, just let me know here.

[pipermerriam]

cc @davesque can you get this issue duplicated in the eth-abi repository. I think this is higher priority than the tuple type work that I initially pointed you at.

I think this also suggests prioritizing ethereum/eth-abi#36 ahead of tuple types might also be beneficial so that it's easier for 3rd party encoders/decoders to be written without requiring a core change to the eth-abi library.

[davesque]

@pipermerriam Sure no problem. Sorry I missed this the other day.

[davesque]

eth-abi issue: ethereum/eth-abi#39

[carver]

So almost all of the work will happen in eth-abi#39, but I'll leave this one open until we upgrade eth-abi in web3.

[carver]

I suspect we'll be seeing Vyper switch to fixedMxN based on vyperlang/vyper#566

Continuing to leave this issue open until that's confirmed.

[dylanjw]

Vyper included the switch from decimal10 to fixed168x10 in vyperlang/vyper#815