* renaming the pipe-form `if:`/`else:` to `ask:`/`otherwise:` to match Bootstrap

* cleaning up visitors to visit `Name`s (though this may cause an unfortunate slowdown in compilation times; we'll have to see)
* adding some minimal tests to desugaring to ensure that `if`/`then`/`else` and `ask:`/`otherwise:` are pretty-printed correctly and independently (they used to share string constants, which was bad)
* un-bit-rotting some other desugaring tests, though there's more to do.