text: Title: TempoDetector batch processing hangs on bad input
  Body: ### Expected behaviour
  
  Run
  
      tempodetector --mirex batch 105247.mp3
  
  It should finish processing, no matter what.
  The attached test file is from [FMA_medium](https://github.com/mdeff/fma).
  
  ### Actual behaviour
  
  It prints a message that the file could not be read (which is correct), but then simply hangs.
  
  I'll provide a fix in a PR shortly.
  
  [105247.mp3.zip](https://github.com/CPJKU/madmom/files/3440586/105247.mp3.zip)
  