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/dynload/io/TestIO.hs

@@ -7,7 +7,7 @@
 module TestIO ( resource_dyn )  where
 
 import API
-import AltData.Dynamic
+import Data.Dynamic
 
 import System.IO
 import System.Posix.Types   ( ProcessID, Fd )