proposal: add async foreach/ienumerator

[lobster2012-user]

async foreach
async ienumerator

while(await enumerator.Move())
{
process((await?) enumerator.Current)
}
.....
async foreach(var a in list)
{
process(a);
}

Thanks.

[svick]

I think this is a duplicate of #43 and #390.

[lobster2012-user]

Thanks. Closed.