Retire wabt

[axic]

Depends on #173 and ewasm/wast2wasm#11.

[axic]

Need to be rebased after #173 is merged.

[axic]

This currently is failing on one test:

# manyFunctions100 manyFunctions100
not ok 1425 RangeError: Maximum call stack size exceeded
  ---
    operator: fail
    at: runner.catch.err (/home/travis/build/ewasm/evm2wasm/tests/runVmTests.js:171:9)
    stack: |-
      Error: RangeError: Maximum call stack size exceeded
          at Test.assert [as _assert] (/home/travis/build/ewasm/evm2wasm/node_modules/tape/lib/test.js:225:54)
          at Test.bound [as _assert] (/home/travis/build/ewasm/evm2wasm/node_modules/tape/lib/test.js:77:32)
          at Test.fail (/home/travis/build/ewasm/evm2wasm/node_modules/tape/lib/test.js:318:10)
          at Test.bound [as fail] (/home/travis/build/ewasm/evm2wasm/node_modules/tape/lib/test.js:77:32)
          at runner.catch.err (/home/travis/build/ewasm/evm2wasm/tests/runVmTests.js:171:9)
          at <anonymous>
          at process._tickCallback (internal/process/next_tick.js:188:7)
  ...

I think this actually is happening inside the emscripten-ized wabt. If that is the case the only chance here is to update wabt and/or recompile it with different emscripten flags.

However, in the long term a better solution would be fixing ewasm/wasm-json-toolkit#19

Lastly, none of this is important if we're moving evm2wasm to C++.

[lrettig]

Closing in favor of #249