prefixed "audio" sliders with 'a'

so we can also have "video" ('v') sliders
disabled unused video/audio source selection
added vdelay slider
camelcased names for sections
prefix "audio" controls with 'A' (in implementation)
fixed camelcase
proper defaults for text-overlay
initialize stream controls/prefs on startup

so the config-file get's actually used...
read pipeline from conf-file
specify default pipeline in conffile