Misc. typos

Found via ` codespell -q 3 -S *.ts,*.xml -L ba,froms,seeked`

rendering/cacher.cpp

@@ -887,7 +887,7 @@ void Cacher::OpenWorker() {
     // opens file resource for FFmpeg and prepares Clip struct for playback
     Footage* m = clip->media()->to_footage();
 
-    // byte array for retriving raw bytes from QString URL
+    // byte array for retrieving raw bytes from QString URL
     QByteArray ba;
 
     // do we have a proxy?

rendering/exportthread.cpp

@@ -275,7 +275,7 @@ bool ExportThread::SetupAudio() {
     return false;
   }
 
-  // Copy paramters from the codec context (set up above) to the output stream
+  // Copy parameters from the codec context (set up above) to the output stream
   ret = avcodec_parameters_from_context(audio_stream->codecpar, acodec_ctx);
   if (ret < 0) {
     qCritical() << "Could not copy audio encoder parameters to output stream." << ret;