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/eval/eval_fn1/Poly.hs

@@ -1,7 +1,7 @@
 {-# OPTIONS -cpp -fglasgow-exts #-} 
 module Poly where
 
-import AltData.Typeable
+import Data.Typeable
 
 data Fn = Fn {fn :: forall t. Eq t => t -> t -> Bool}