Some cleanup & 2.10 deprecation upheaval

Enacts the 2.10 drop.
Removes deprecations w.r.t. Scala 2.11.
Removes unused members, imports.
non-trivial parts commented on below.

I don't think this is right. I think what is needed here is the getter name.

If we inline the method, we get:
```scala
nme.setterToGetter(rt.name.toTermName)
=>
rt.name.toTermName.getterName
```

Maybe we can omit the `toTermName`, but the result should be the getter.