diff layer/LayerFactory.cpp @ 69:6dad2724f3aa

* Ensure plugin parameters for a transform are saved in the .sv file and
  restored in case the plugin has to be run again
* Make plugin dialog offer options for mixdown/single-channel use if the
  file has more than one channels but the plugin only accepts one
* Fix incorrect samplerate playback for second file loaded if its samplerate
  differed from first
* Add Zoom to Fit and Select Visible Range menu options, split out Import
  Audio into main model and secondary model options
* Add stubs for cut, copy and paste operations (not implemented yet)