Memory management

[Michael Stoll <Michael_Stoll@math.uni-bonn.de>]

Coming back to my latest patch of gtrunc() -- I'm not sure about
the following two points.

(1) Should the result of a function always be in a contiguous piece
    of stack memory ?
    (If not, we could simply use  y[1] = x[4]  instead of lcopy((GEN)x[4]).)
(2) Should the result always be left on top of the stack ?
    (If yes, we would have to return gcopy((GEN)x[4]) instead of
    simply (GEN)x[4].)

Maybe one of the experts could drop a hint.

Thanks,
        Michael