DVB scan files use 8PSK, not PSK_8

Scanfiles produced by hand or by w_scan set the constalation field as
8PSK, 16APSK or 32APSK, not as PSK_8, APSK_16 or APSK_32.

Because these strings appear to be used in other code and more
importantly current config files, keeping the old tables to not break
everybodies config.

Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>
DVB-S[2] uses a rolloff factor, not hierachy

Currently, TV-Headend assumes that the 5th field is hierachy. This is
incorrect, the 5th field in a scanfile for DVB-S[2] is rolloff.

This patch adds support for rolloff on scan and sets it approperatly.

Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>