GitHub #139: Add "properties" to Processor (for lv2 bounds setting)

@property(foo=bar)  will set (saved/restored) property foo to value bar
@property("foo") will log the value of foo
@property_delete("foo") will remove the property

At LV2 save time, each [inlet] is checked for the following properties:
  bounds_minimum
  bounds_maximum
  bounds_default

Future will add some type properties as well, right now it is just numbers