As the parser now flattens out the instructions and inserts synthetic
nesting/structured instructions where needed, we can treat the whole
thing as a simple parsed bytecode stream.
This currently knows how to execute the following instructions:
- unreachable
- nop
- local.get
- local.set
- {i,f}{32,64}.const
- block
- loop
- if/else
- branch / branch_if
- i32_add
- i32_and/or/xor
- i32_ne
This also extends the 'wasm' utility to optionally execute the first
function in the module with optionally user-supplied arguments.
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 :^)
