Inspector channel properties don't work as expected

[BatchDrake]

When the channel offset is set in the inspector tab, the frequency shift is being applied to the channel output and not the input (as it ought to be). Additionally, when the shift is above the resolution bandwidth, the channelizer jumps to the next bin (this is correct), producing a completely different spectrum. This shows up as a characteristic sawtooth pattern in the inspector waterfall:

In some situations, a post-channelization shift may be interesting (especially for skewed signals like SSB). This fix should allow adjusting both pre and post channelization frequency offsets from the inspector tab.