Previously, this was parsing only one kind because I mistakenly assumed
that they all had the same shape, now it can parse two kinds, and will
return NotImplemented for the rest.
With this, the parser should technically be able to parse all wasm
modules. Any parse failure on correct modules should henceforth be
labelled a bug :^)
With this, we can parse a module at least as simple as the following C
code would generate:
```c
int add(int x, int y) {
if (x > y)
return x + y;
return y - x; // Haha goteeem
}
```
It's much better to tell the user "hey, the magic numbers don't check
out" than "oh there was a problem with your input" :P
Also refactors some stuff to make it possible to efficiently use the
parser error enum without it getting in the way.
This can currently parse a really simple module.
Note that it cannot parse the DataCount section, and it's still missing
almost all of the instructions.
This commit also adds a 'wasm' test utility that tries to parse a given
webassembly binary file.
It currently does nothing but exit when the parse fails, but it's a
start :^)
