Revert "Fixed expected result in added test"

This reverts commit 0f8f39e71fc912b8a5e4db1323041f3602f7192c.
Revert "Added test relative to issue #184"

This reverts commit 1684ec3136e90d3181985bf6c2f8aef2d5c00ba3.
Revert "Removed unnecessary Module block"

This reverts commit d66bf3e0448e3e3b95a4e2fe0ccefdc111dde07a.
Revert "Possible fix for D[Cos[t],t] behaviour"

This reverts commit 11c6eecf77718e697e38348037131eb2912d12af.