Add a simple test suite

tests/README

tests/extensions/TypeOperators.hs

tests/extensions/TypeOperators.html.ref

tests/pre-2.0-tests/A.hs

tests/pre-2.0-tests/A.html.ref

tests/pre-2.0-tests/B.hs

tests/pre-2.0-tests/B.html.ref

tests/pre-2.0-tests/Bug1.hs

tests/pre-2.0-tests/Bug1.html.ref

tests/pre-2.0-tests/Bug2.hs

tests/pre-2.0-tests/Bug2.html.ref

tests/pre-2.0-tests/Bug3.hs

tests/pre-2.0-tests/Bug3.html.ref

tests/pre-2.0-tests/Bug4.hs

tests/pre-2.0-tests/Bug4.html.ref

tests/pre-2.0-tests/Bug6.hs

tests/pre-2.0-tests/Bug6.html.ref

tests/pre-2.0-tests/Bug7.hs

tests/pre-2.0-tests/Bug7.html.ref

tests/pre-2.0-tests/Bug8.hs