* VST: add support for graphics
* VST: add support for plug-ins without processReplacing()
  (will require out-of-place buffers just like in plugin~_ladspa.c)
* VST: add support for VST2 synthesizers
* make is possible to use both LADSPA and VST plug-ins in a single Pd
  patch (i.e. act as either LADSPA or VST host "on demand")