Constant-Q library and Vamp plugin, v1.1

[cannam]

A new release of this Constant-Q transform library and Vamp plugin is now available:

  https://code.soundsoftware.ac.uk/projects/constant-q-cpp

Most of the changes concern code organisation, for example giving the Chromagram class its own formal API in the underlying library. However, there is also a fix to label ordering in the Vamp plugin.