Adding a spec for the Transact refactoring.

More of a placeholder, as only 2 very simple tests are coded.
Adding imports in Transact, and more tests.

Convoluted.expected: corrected 2 calls from putMVar to putTMVar

SimpleConfusion.expected: corrected 1 call from newEmptyMVarIO to newEmptyTMVarIO

TransactSpec.hs:
* removed old code comment.
* added a test case for SimpleConfusion, in which you try to refactor an MVar which is not used as an MVar. Shouldn't create problems such as trying to refactor those functions which don't use MVars.

Transact.hs:
* now adding an import declaration for Control.Concurrent.STM. It's still buggy as:
  * adding the declaration doesn't creates a newline after it.
  * adding a declaration when the last declaration is commented ends up appending the new declaration to the comment.
  The tests for Transact reflect this.

* trying to fix a bug about grabbing an MVar and misinterpreting it as a different type of variable.