Don't hop to the first enclosing, non-silent context when typing refinements.

Closes SI-5305.

This reverts a few lines of e5cfe47a19, which was a remedy for SI-3614 and SI-3856*. I added a test case for the former, the
latter was already tested. Both tests pass after this change, and they do so with the old and new pattern matcher.

But does this change still "avoid trees with null types in presentation compiler"? What was the intent of the context hopping in the first place?

* Based on this comment: https://issues.scala-lang.org/browse/SI-3614?focusedCommentId=50477&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-50477, which elaborates further than the commit comment of e5cfe47a19.
Add more logging.
Fixes SI-4717.

A lazy val declared inside an anonymous class inside a specialized
context no longer crashes Duplicators.

Previously, a duplicated lazy val was assigned to the wrong owner
in Duplicators:

    def x[B >: A]: Unit = new Bounds[B] {
      lazy val it = ???  // def or val okay
    }

Above, the `it` in `$anon` in `x$mcZ$sp` had its owner set to `x$mcZ$sp`
instead of `$anon`. This crashed the typer when it had to retype its
lazy accessor, because there was no `lazy var it` in `$anon$`.
Furthermore, the duplicated symbol wasn't being added to the list of
declarations of `$anon`.

Changes:
1) `invalidate` in Duplicators takes an additional parameter which is
the new owner of the new symbol that has to be duplicated. If this parameter
is set to `NoSymbol`, then the new owner is `context.owner`, as before.
2) the newly created lazy val symbol is being added to the list of
declarations of its new owner.

Removes debugging output from the previous commit.

Review by dragos.
@mention dragos
Further fixes SI-4717.

Only adding a lazy val into list of declarations if the owner is a class.

Review by dragos.
@mention dragos
Fixes previous commit.

Should be checking if the owner of the new symbol is a class, not the new symbol itself.
Adding the Actor Migration Kit.

  Kit consists of:
    1) The StashingActor which adopts an interface similar to Akka.
    2) Props mockup for creating Akka like code
    3) Pattern mockup
    4) Test cases for every step in the migration.
    5) MigrationSystem which will paired on the Akka side.

  Review of the code : @phaller
  Review of the build: @jsuereth
Fixes SI-5804.

The hash table initialSize method is now within
the the hashset and hashmap classes, and not in the companion.
Overriding this method now yields hashmaps and hashsets
of the proper initial capacity.

Review by @phaller.
Fix to Scaladoc keyboard shortcuts for Firefox
Fix @varargs forwarder generation in the presence of nested templates.

Makes `newMembers` a Map[Symbol, Buffer[Tree]] to ensure we add the forwarders to the right template.

Closes SI-5125.
Improve test for SI-5125.

Uncomment a line, as was the intent.
Pending test for SI-3899.

The super accessor for the Java varargs method impedes Uncurry's
efforts to convert repeated arguments to an Array. I'm not sure how
to fix that.
Test case closes SI-3880.

virtpatmat ftw.
Consider method-scoped companions in the implicit scope.

Fixes SI-4975.

I'll reproduce a relevant snippet of dialogue from Namers#companionSymbolOf:

/** The companion class or companion module of `original`.
   *  Calling .companionModule does not work for classes defined inside methods.
   *
   *  !!! Then why don't we fix companionModule? Does the presence of these
   *  methods imply all the places in the compiler calling sym.companionModule are
   *  bugs waiting to be reported? If not, why not? When exactly do we need to
   *  call this method?
   */
  def companionSymbolOf(original: Symbol, ctx: Context): Symbol = {

This was one such bug.
SI-5760: Improve error message for package$Klass conflict with Klass

Added a clarification to DoubleDefError for when the previous symbol
was in the package object but current symbol is not.

This was actually supposed to be an opportunity to hack partest to
run the two-step failing compilation, but somebody beat me to it and my
rebase failed.

The next hacking opportunity might be to add .pt script files!  The
possibilities are endless.
Closes SI-5735, this could also potentially fix a SO problem that @adriaanm was experiencing in IDE but could not reproduce it.
Merge pull request #576 from axel22/issue/4717

Fix SI-4717: lazy val declared inside an anonymous class inside a specialized
context no longer crashes Duplicators.
Merge pull request #587 from retronym/ticket/5125

Fix @varargs forwarder generation in the presence of nested templates.
Merge pull request #590 from retronym/ticket/3899

Pending test for SI-3899.
Merge pull request #591 from retronym/ticket/3888

Test case closes SI-3880.
Merge pull request #593 from som-snytt/ticket/5760-pkgobj-warn

SI-5760: Improve error message for package$Klass conflict with Klass