Investigate how Solidity could output wasm/llvm

[axic]

Current Solidity code is tied to emitting EVM opcodes. Investigate the possibility of moving it to LLVM or emitting WASM directly.

[axic]

Solidity currently has two backends operating on the internal AST:

• codegen (for EVM)
• formal (for Why3)

A third could be added, probably based off the why3 code, to output WAST as a first step.

[axic]

Being handled by https://github.com/ethereum/solidity/pull/2233