Proposal for porting D runtime to WebAssembly

[Elronnd]

>> (_start is the wasm's equivalent of _Dmain)
> Not really; _start (in libc) is used on Linux too, which sets 
> up the C runtime, then calls C main, which calls druntime's 
> _d_run_main which in turn calls _Dmain.

Small correction: _start generally calls __libc_start_main() or 
similar, with the addresses of main, argc, argv, envp, module ini 
and fini, and possibly some other stuff I forgot about.