SI-5314 - CPS transform of return statement fails

Enable return expressions in CPS code if they are in tail position. Note that tail returns are
only removed in methods that do not call `shift` or `reset` (otherwise, an error is reported).

Addresses the issues pointed out in a previous pull request:
https://github.com/scala/scala/pull/720

- Addresses all issues mentioned here:
  https://github.com/scala/scala/pull/720#issuecomment-6429705

- Move transformation methods to SelectiveANFTransform.scala:
  https://github.com/scala/scala/pull/720#commitcomment-1477497

- Do not keep a list of tail returns.

Tests:
- continuations-neg/t5314-missing-result-type.scala
- continuations-neg/t5314-type-error.scala
- continuations-neg/t5314-npe.scala
- continuations-neg/t5314-return-reset.scala
- continuations-run/t5314.scala
- continuations-run/t5314-2.scala
- continuations-run/t5314-3.scala
Replace CheckCPSMethodTraverser with additional parameter on transformer methods

Other fixes:

- remove CPSUtils.allCPSMethods
- add clarifying comment about adding a plus marker to a return expression
Add missing cases in tail return transform

Disabled warnings that no longer apply because of tail returns.
Add several test cases.
Revert "Add missing cases in tail return transform"

This reverts commit 8d020fab9758ced93eb18fa51c906b95ec104aed.
Simplify the adaptation of types of return expressions

Add `adaptTypeOfReturn` hook to `AnnotationCheckers`.
Move adaptation of types of return expressions from `addAnnotations`
to `typedReturn` via `adaptTypeOfReturn` hook.

This resolves an inconsistency where previously types could have
a plus marker without additional CPS annotations. This also adds
additional test cases.
Improve doc comment on adaptTypeOfReturn in CPSAnnotationChecker
SI-6170 Revert #456 "Upgrade jQuery from 1.4.2 to 1.7.2"

This reverts commit b6c0e4478616a1252d65754a40c5dcbfc6554b36 because it caused SI-6170,
after this revert, the left "search" panel of scaladoc should be resizable again.
SI-4857 fixes showall/hideall Scaladoc interface bug
Automatically highlight and scroll to linked-to members
Rank based take/drop/slice.

Tree navigation based on node rank is faster than using compare
method. rank is simply count(tree.left) + 1.
Fixes SI-6337 by disallowing nested value classes.

It seems for the moment too hard to allow this, and the functionality to have value classes wrap other value classes does not seem essential.
Fixed comment.
Removed many @inline annotations and final modifiers.

It is my belief that these @inlines and finals landed between
unhelpful and harmful. I am sure this will be disputed in some
cases. It's too much and too difficult to measure except in the
aggregate unless we have specific @inline sites to discuss.
I don't know upon whom the burden of proof lies.  I think we
should err on the side given here, since there is no evidence
of any consistent rationale being applied and it is easy to
verify the negative impact scala compiler inlining can have on
hotspot's far more sophisticated inlining.
enable integer multiplication/divison on FiniteDuration, see SI-6389

- without this "2.seconds * 2" will not return FiniteDuration but
  Duration
- added test case verifying this behavior
- matches normal arithmetics: integers throw on div-by-zero while
  doubles yield infinity; extended here to include overflow protection
  on integer multiplication
existentially typed expansions now work fine

If one tries to compile the following code with the parent of this commit:

  ru.reify(new Object().getClass)

then the following error will occur:

  Test.scala:2: error: type mismatch;
    found   : $u.Expr[Class[_ <: Object]]
    required: reflect.runtime.universe.Expr[Class[?0(in value <local Test>)]]
              where type ?0(in value <local Test>) <: Object
    ru.reify(new Object().getClass)
            ^

This happens because macro expansions are always typechecked against the
return type of their macro definitions instantiated in the context of expandee.

In this case the expected type contains skolems which are incompatible
with wildcards in the type of the expansion.

I tried all the incantations I could think of - without any success.
Luckily I met Martin who pointed me at the same problem solved in adapt
(see the diff w.r.t Typers.scala).
test case closes SI-5418

Now, when the existential reification bug is fixed, I've been able
to take a look at SI-5418, and, apparently, the problem with importers
has fixed itself during these 9 months of the bug being active.
SI-6336 Now also catches return types

As Mark's comments on SI-6336 shows, we also need to disallow value classes
as return types of structural types.
Retain Ordering in drop/take/slice signatures.

Addresses code review feedback by @axel22.
Add RedBlackTree tests for take/drop/slice.

Addresses review feedback by axel22.
Fixes SI-6305 scala.tools.nsc.io split between jars.

* migrates scala.tools.nsc.io portions into scala.reflect.io
* marks all classes in scala.reflect.io experimental/internal
* rewires src/reflect to use new io locations
* creates forwarders in scala.tools.nsci.io package object.