noSelfType doesn't have a symbol
don't let NoType leak
some refactoring in self type conversion
relax attribute checking for literals
works around https://groups.google.com/forum/#!topic/scala-internals/gppfuY7-tdA
apparently quasiquotes can't match `<unapply-selector>`
Aux.Parent(..., List(List())) is now normalized to Aux.Parent(..., Nil)

We can't discern `extends C()` and `extends C` anyway, so it doesn't matter
much which of those representation we use for the time being.
failure logging in converters now also accounts for assertions
migrates an occasional assert to require
unapplication of a case class is more weird that I thought
support for old-style macros