Bug#829563: cecilia: Please update the package description and remove references to CSound

[Roberto]

Package: cecilia
Severity: minor

Cecilia is not based on CSound anymore, it uses Pyo audio engine since
version 5, but the package description still mentions the behaviour of
Cecilia version 4 and previous.

Possible new description taken from Cecilia documentation:

  Cecilia is an audio signal processing environment aimed at sound
  designers. It lets you create your own GUI using a simple syntax and comes
  with many original built-in modules and presets for sound effects and
  synthesis.