wish: more precise ETA

[Kiss Gabor]

When I restart an interrupted download and progress report is
on (-P option) the calculated remaining time is totally unusable.
(Even worse if meanwhile I play with --bwlimit option.)
The actual_speed computation should not be based on the
(total_file_size/time_elapsed_since_start) quotient.
Much realistic result could be achieved by a FIR filter.
Even the most simple case, the
(bytes_arrived_in_the_last_N_seconds/N_seconds) value
would give a better actual_speed value.

Gabor
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I'm not a list member. Please Cc the answers to me also.