[LAD] Saving plugin presets

[Paul Davis]

I don't really think there is a "good" answer to the format question.
What matters is whether there is a simple code-level solution to save
presets and to reload them. if there is, it doesn't matter what the
format is. ardour has been using turtle (RDF-related) for years because
that was assessed early in LADSPA's life as the best choice for a
variety of reasons. but it really doesn't matter since we have functions
to save&restore presets and we don't care what is inside the preset
files. 

the real problem is there is no library associated with either LADSPA or
LV2 and so there is nowhere obvious to put this kind of code.