introduces setInner function
Introduced setAndConfirm function
emit valueChangeRequest if connected
Use new request signal for CO "Play"
minor style change
additional docu and fixes from review
fixed widget toggle state
fixed CO "play" meaning to "play command accepted". This makes a
differnce only during loading a track. Now "play" becomes always 1 when
a track command is received while loading.
removed debug output
Remove virtual EngineFilterButterworth8::setFrequencyCorners(), remove unused freqCorner2 in Low and High filter (fix warnings)
Merge pull request #61 from xorik/butterworth-warning-fix

Fix warnings in enginefilterbutterworth8.cpp
Merge pull request #57 from daschuer/co_request

Co request