Remove tabs, trailing spaces, and write-only variables

This partially reverts commit add821b0.

Caused by [231a9671]
Sorry for the disturbance

(we might need a PSK box later)

This merges the Linux DVB and Windows BDA backend behind the same
plugin-internal interface.
Like the existing BDA plugin, this does not support PID filters,
signal levels nor DVB-S2.

pulse: let pulseaudio define prebuffer/minrequest and use that as buffersize, also change maxlength to 100ms

It's more along pulseaudio recommendations, and we don't really need to define those
ourself. Maxlength is defined to keep latency in someway in limits. Please tell if
this acts for you.

This will do for now to meet popular demand