Require reserved instruction bytes to be one byte (WebAssembly#922)

The spec requires that the reserved bytes in `call_indirect`,
`memory.grow`, and `memory.size` to be one zero byte. This means that we
cannot accept `0x80 0x00`, or other "long" LEB128 encodings of zero.

[appveyor] Another try at getting deploys working

[appveyor] Maybe fix deploy issues

Some fixes for binary releases (WebAssembly#879)

* Create the artifacts before they are packaged (`before_deploy` happens
afterward)
* MacOS doesn't have sha256, so use python

Binary releases for travis/appveyor (WebAssembly#876)

Fixes WebAssembly#875, maybe.

Read and write module names in the names section (WebAssembly#831)

Fix type-checking bug in br_if w/ polymorphic stack (WebAssembly#589)

Similar to issue WebAssembly#586, it is necessary to pop and re-push the type on
the top of the stack when validating br_if, because otherwise the
concerete type is not pushed on the stack (i.e. the top remains
polymorphic).

Fixes WebAssembly#588.

Change NULL -> nullptr (WebAssembly#315)

Also switch to using C++11.

Update tests syntax to new flat syntax (WebAssembly#180)

* more converted tests
* more tests plus fix to broken test
* fixed broken tests
* converted more tests and fixed issues with previously submitted 'interp/binary.txt' and 'nested-if.txt'

Use `--recursive` in clone example to make easier. (WebAssembly#114)