member descriptor ics

trying to fill in rewriting holes... for this one I had to some support for doubles and some `mov` variants in the assembler and rewriter. Kind of hacky/lazy...
I think you are supposed to extend function arguments to 32 bits -- this is what the `make test_cpp_asm` target is nice for:

```C++
void* boxBool(bool b);

void* foo(bool *b) {
    return boxBool(*b);
}
```
`make test_cpp_asm`
```
Disassembly of section .text:

0000000000000000 <_Z3fooPb>:
   0:   0f b6 3f                movzbl (%rdi),%edi
   3:   e9 00 00 00 00          jmpq   8 <_Z3fooPb+0x8>
```