GitHub #139: Initial save-as-lv2 checkpoint.  No TTL file created yet.
GitHub #139: Checkpoint on LV2 plugin save.

Plugin saving is mostly working, but there are remaining problems with loading the
plugin library if multiple different patches are loaded in the same host.  Rework will be
required.
GitHub #139: Use lv2_lib_descriptor API to manage URI discovery
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
Merge pull request #145 from bgribble/savelv2-139

Merging this to master