Changes

make block arg and temp def use visitNode: to style comment in shout

By definition an abstract class will not implement all the logic to work
in standalone. Thus, RBExplicitRequirementMethodsRule should not fail on
abstract classes.

Dictionary and SmallDictionary #values can use new:streamContents:
(#keys is doing that already).
Speed is not impacted as the implemention does exactly the same,

- use NECEntry instad of CompletionEntry - cleanup NECEntry a bit     -
remove #type ivar     - add node ivar     - remove #isLocal and
#isSelector (not used)     - use #lookupSelector, remove lookupSelector:
class:

small fix

- remove atCompletionPosition from TextEditor as we only use it from the
Rubric editor - completionDescription is not needed anymore (it comes
not from the entries, not the AST node)

move #selectedClassOrMetaClass to not be extension, there are a lot of
these in the system and they are used not only for completion