Pause the dac ticking when the app is paused and we're not looping

paused = the app goes into the background. when the thread is ticking in
the background, it gets put on low priority which results in stuttering
and pops in the speaker. So if we're not looping, then chances are we
don't care about keeping the audio playing in the background, so we can
pause the dac thread.
Don't show backpress dialog

we fixed the pop pop :)
Add Theremin instrument

and tweak the order a bit to make the awesome ones first
Remove debuggable mode
Move TimbreTab below InstrumentManagerTab

timbre kinda sucks at the moment :/. it makes more logical sense to put
with the FX Tab, but seeing as how it's the second tab people will see,
I think it sets the wrong tone for the app. there is more exciting stuff
in the Insutrment Manager tab
Update version to 2.0.4 #18

 #i-have-pop-pop-in-the-attic