stats: pass parent string into constructor & enable debug if callback not defined

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
dvbtee: dont reinvent the wheel - delete scale_unit and use stats_scale_unit instead

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
stats: correct debug text to say 'continuity error' instead of 'discontinuity'

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
stats: make debug less verbose by default

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
stats: remove dead code from when 'timenow' was passed

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>