Effectively a revert of previous commit, fixing #542, where this was
added to stop linters complaining about `REQUIRE_THROWS_AS` used like
`REQUIRE_THROWS_AS(expr, std::exception);`, which would be slicing the
caught exception. Now it is user's responsibility to pass us proper
exception type.
Closes#833 which wanted to add `typename`, so that the construct works
in a template, but that would not work with MSVC and older GCC's, as
having `typename` outside of a template is allowed only from C++11
onward.
