Adapt to work with GHC 6.12

- Adapted the package to work with GHC 6.12
- Plugins that depend on the old base3 are currently
  not correctly loaded as the plugin loaded misses
  the dependence on syb (leading to unresolved symbols)
- Cleaned up most of the testsuite (there are still
  some outstanding failures, of which only one
  demonstrates a bug in the plugins library as far
  as I can see — see previous bullet point)
- Cleaned out a little cruft (but more could be done)

testsuite/pdynload/poly/Plugin.hs

@@ -1,9 +1,11 @@
 module Plugin where
 
+import Data.Typeable
+import Data.Generics.Aliases
 import Data.Generics.Schemes
 
 import API
 
 resource = rsrc { 
-     field = id listify
+     field = id listify :: Typeable r => (r -> Bool) -> GenericQ [r]
 }