Major bug: audio filtering never actually worked

We filtered the audio after it was already processed by core, i.e. it was never used
@mwuttke97 @tux3 @Dubslow pls

src/coreav.cpp

@@ -256,6 +256,11 @@ void Core::sendCallAudio(int callId, ToxAv* toxav)
 
     if (Audio::tryCaptureSamples(buf, framesize))
     {
+#ifdef QTOX_FILTER_AUDIO
+        if (filterer[callId])
+            filterer[callId]->filterAudio((int16_t*) buf, framesize);
+#endif
+
         uint8_t dest[bufsize];
         int r;
         if ((r = toxav_prepare_audio_frame(toxav, callId, dest, framesize*2, (int16_t*)buf, framesize)) < 0)
@@ -265,11 +270,6 @@ void Core::sendCallAudio(int callId, ToxAv* toxav)
             return;
         }
 
-#ifdef QTOX_FILTER_AUDIO
-        if (filterer[callId])
-            filterer[callId]->filterAudio((int16_t*) buf, framesize);
-#endif
-
         if ((r = toxav_send_audio(toxav, callId, dest, r)) < 0)
         {
             qDebug() << "Core: toxav_send_audio error";