Implement OUT node

I guess this isn't just a NOP, it's actually a MOV.  The remainder of
the C++ wrapper handles copying code to the output so it can actually
be used, so there's not really anything we need to do.  This MOV
should get completely elided by the optimizer, so it's really just a
NOP :).
Enable proper VCD dumps

All I did here was output the module heirarchy to the VCD file, the
rest was already working fine.
Check VCD output with vcddiff

This change includes a VCD file in the test cases (which was generated
using Chisel) and checks that it matches the output from the running
the generated LLVM code.