Test suite for Haskell2010

To keep track of progress and to ward off regressions, the test suite now have a section for Haskell2010 compatibility checks:

# runhaskell Main.hs -t Haskell2010 --plain | tail -n 4
         Test Cases  Total
 Passed  0           0
 Failed  6           6
 Total   6           6

The tests only cover a small part of the Haskell2010 specification and none of them pass yet.