SI-6448 Collecting the spoils of PartialFun#runWith

Avoids calling both `isDefinedAt` and `apply`. This pathological
case that would benefit the most looks like:

  xs collect {
    case x if {expensive(); true} => x
  }

The typical change looks like:

-    for (x <- this) if (pf.isDefinedAt(x)) b += pf(x)
+    foreach(pf.runWith(b += _))

Incorporates feedback provided by Pavel Pavlov:

  https://github.com/retronym/scala/commit/ef5430

A few more opportunities for optimization are noted in the
`Pending` section of the enclosed test. `Iterator.collect`
would be nice, but a solution eludes me.

Calling the guard less frequently does change the behaviour
of these functions in an obervable way, but not contravene
the documented semantics. That said, there is an alternative
opinion on the comment of the ticket:

  https://issues.scala-lang.org/browse/SI-6448
Associate correct names to e-mails, correct or not

This is used by git log to produce names with certain formats, and
is used by the release notes tool as well. Helpful if you have commits
with Author not set correctly, as did I.

I'm also including Aleksandar Prokopec and his friend Aleksandar Pokopec,
as well as Pavel Pavlov, both of whom have commits appearing under more
than one name.

I'm not including others who have not set a full name, but don't have
commits appearing under more than one name.
Fix for SI-6357, cycle with value classes.

Don't force the owner info.
Added -Xdev setting... you know, for devs

A setting we developers can give all the time and expect to
hear useful things without being buried in debugging output.
As the comment says:

  This is for WARNINGS which should reach the ears of scala
  developers whenever they occur, but are not useful for normal
  users. They should be precise, explanatory, and infrequent. Please
  don't use this as a logging mechanism. !!! is prefixed to all
  messages issued via this route to make them visually distinct.

This is what I always intended for "debugwarn", the method
I have deprecated in favor of the more accurate:

  def devWarning(msg: => String): Unit

In this VERY SAME COMMIT, I performed the CLOSELY RELATED
task of quieting down an -Xlint warning which had become too
noisy thanks to implicit classes tickling it. I tightened that
warn condition to include both -Xlint and -Xdev.
Merge pull request #1626 from paulp/issue/6357

Fix for SI-6357, cycle with value classes.
Removed unused imports in swing.
Remove unused imports in partest.
Remove unused imports in continuations.
Remove unused imports in library.
Deal with possibly spurious warning in Macros.
applyOrElse is a synthetic method.
Commenting out unused members.

I want to get this commit into the history because
the tests pass here, which demonstrates that every commented
out method is not only unnecessary internally but has zero
test coverage. Since I know (based on the occasional source
code comment, or more often based on knowing something about
other source bases) that some of these can't be removed
without breaking other things, I want to at least record
a snapshot of the identities of all these unused and
untested methods.

This commit will be reverted; then there will be another
commit which removes the subset of these methods which I
believe to be removable. The remainder are in great need of
tests which exercise the interfaces upon which other
repositories depend.
Revert "Commenting out unused members."

This reverts commit 951fc3a486.
Removing ancient comments and pointless comments.

Translating <code></code> into backticks.

Removed the "@param tree ..." blocks which have been
taunting me for half a decade now.

Removed commented-out blocks of code which had been
sitting there for two years or more.
Some files removed in their entirety.

And small associated changes.
Members removed from the repl.

There were a whole lot of these.
Members removed from scala.reflect.io.

Mostly hailing from a long-ago day when I imagined I was
writing a general purpose library. We dodged that bullet.
Members removed from partest.

It has accreted its share through the bumpy years.
Members removed in the backend.
Members removed in scala.reflect.

Not a bad showing for a newcomer. Of course most of this
code predates scala.reflect by a lot.