2.2.40 Ultraspectra: six analog input modes driving the front end relays. input_mode (50r_2v, 1k_2v, 1k_3v, 1k_4v, 1k_5v, 1k_8v) drives relays 2, 3 and 4 in a safe order; .impedance and .range become views of it. Merged from ultraspectra-input-range, built as 2.2.38/2.2.39-STAGING.