Drop structural instances from docs

Structural instances (i.e. use `with` instead of `new` for anonymous classes)
are not part of this PR.

Author: odersky

docs/docs/reference/other-new-features/creator-applications.md

@@ -41,60 +41,3 @@ caused numerous problems, including
  - overloading ambiguities
  - overriding errors
  - shadowing of user-defined `apply` methods by more specific auto-generated ones.
-
-### Structural Instances
-
-Structural instances are a replacement for anonymous classes.
-Example:
-```scala
-trait Person {
-  def name: String
-  def age: Int
-}
-// Anonymous class
-new Person {
-  def name = "Lara"
-  def age = 22
-}
-// Structural instance
-Person with {
-  def name = "Lara"
-  def age = 22
-}
-```
-A structural instance expression consists of the implemented class(es) or trait(s) (`Person` in the code above), followed by the reserved word `with` and definitions that implement or override class members.
-
-Structural instances can be have more than one parent. In this case,
-
-
-### Translation
-
-Structural instances map to expressions with `new` as follows.
-
-A structural instance with a single parent `T` and empty definitions
-```scala
-T(args) with { }
-```
-maps to
-```
-new T(args)
-```
-
-A structural instance with multiple parents and/or non-empty definitions
-
-```scala
-T(args1) with U(args2) with { defs }
-```
-maps to
-```
-{ class $anon extends T(args1), U(args2) { defs} ; new $anon }
-```
-This means that every instance creation expression can be written without `new`, using either a creator application or, where this is not possible, a structural instance expression.
-
-### Syntax
-
-```
-Expr1               ::=  ... | StructuralInstance
-StructuralInstance  ::=  ConstrApp {‘with’ ConstrApp} ‘with’ TemplateBody
-```
-