Vamp Plugin SDK

Merge from branch c++11-mutex

Update versions throughout to 2.8

Copyright dates

KissFFT copyright notes

Add PluginConfiguration, PluginStaticData, and LoadRequest structures, and use them in PluginLoader

Updates for v2.6

Copyright dates

Make the simple base-fft implementation accessible for use by plugins as well. Bump version to 2.4

Update versions throughout

• Update versions to 2.2 throughout; also add script used to do this

• Add documentation about backward compatibility

• tidy

• Add platform README files

• More tweaks to fixed-tempo estimator

• Update README to describe example plugins VC project file and
  include a note about exporting the entry point symbol

...

• OS/X build stuff

• update .la files

• doc updates

• Merge from host-factory-stuff branch: this adds several helper classes in
  the hostext directory that should make a host's life much easier. This
  will become version 1.1 of the SDK, eventually.

• Put hostext stuff in the HostExt sub-namespace
• Tidy up system-specific stuff in PluginLoader
• Make PluginLoader return a deletion-notifying wrapper which permits the
  library to be unloaded when no longer in use
• Add PluginChannelAdapter
• Make vamp-simple-host use PluginChannelAdapter, and use the PluginLoader...

• Split out the host adapter code into a separate host sdk library.
  Plugins link against libvamp-sdk, hosts against libvamp-hostsdk.

• fix to step size for frequency domain plugins
• textual updates

...

• Add a function to look up the Vamp plugin path for the current platform.

• Add make install stage and pkgconfig files.
  (This bit is rather Linux-specific.)

• Some textual changes

• Add README file