[RFC] `time' builtin

[Jose E. Marchesi]

Hi people!

So we need a `time' builtin function to get the time :)

The main motivation is to build seeds for the already existing `rand':

  fun rand = (uint<32> seed = 0) int<32>:

Now the question is: what would be a good prototype for `time'?  What
should it return?  We could:

a) Make it return seconds since the Epoch, or
b) something more elaborated and precise like a struct tm.

Note that we already have a `ptime' function in the standard library
that gives a date in seconds since the Epoch prints a human-readable
version of it:

  fun ptime = (uint<64> seconds) void:

So maybe a) is more than enough... thoughts?