Update tools/epfl-publish

Currently, during each Scala nightly build, the epfl-publish script rsyncs the resulting dists/archives to the repository machine (chara).

Now, as a result of a change introduced a while back, dists/archives/ now also contains a symbolic link, created at the end of the build when the targets "pack-archives.latest.*" are invoked (in src/build/pack.xml). That was introduced in:

scala/scala@506bcfe71c93160ebfa0ca9b8b170b4b54e844e9
scala/scala@cb99853c8655686dae1288cbcd44a42cf1ea6609

This link, created in dists/archives/, is copied over as-is at the end of the rsync to chara by epfl-publish. On chara, however, the link points to an invalid target (the path is absolute).

Separately, the repository directory on chara is rsync'd every 30 minutes over to the machine that serves www.scala-lang.org, via cron. Rsynch finds that the link target does not exist, and generates an email with the crontab log, which is then duly sent to a system mailbox. Every 30 minutes. Since March. Needless to say, the mailbox is pretty large by now.

The fix is trivial, but this needs to be included in all the branches that are tested during the nightly. Since RC2 has just been cut, and the code frozen, I'm not sure how this change can be included without disruption; therefore, I'll just send a pull request on 2.10.0-wip, and let Josh/Paul take the appropriate steps.
SI-6646 Fix regression in for desugaring.

The early check in the parser of pattern irrefutability,
added in c82ecab, failed to consider InitCaps and
`backquoted` identifiers.
SI-6644 Account for varargs in extmethod forwarder

Which sounded difficult, so instead I offshored the work
to the friendly republic of TreeGen.
SI-6646 `ident` or Ident is always new binding.

The previous commit regressed in these cases:

    // no withFilter
    for (X <- List("A single ident is always a pattern")) println(X)
    for (`x` <- List("A single ident is always a pattern")) println(`x`)

At the top level of the LHS of a <-, such identifiers represent
new bindings, not stable identifier patterns.
Update comment.
Merge pull request #1606 from retronym/ticket/6646

SI-6646 Fix regression in for desugaring.
Merge pull request #1601 from cunei/patch-1

Update tools/epfl-publish
Merge pull request #1608 from retronym/ticket/6644

SI-6644 Account for varargs in extmethod forwarder
SI-6673 fixes macro problems with eta expansions

Eta expansions previously caused the typer to disable macros. That was
done in order to detect eta expansion of macro defs and show the user
an appropriate error message.

Macros were disabled because to find out whether we're expanding
a macro def, we need to get its symbol, and to get a symbol of something
we need to typecheck that something. However typechecking automatically
expands macros, so, unless we disable macros, after a typecheck we won't
be able to analyze macro occurrences anymore.

Unfortunately this solution has a fatal flaw. By disabling macros we
not only prevent the eta-expandee from macro expanding, but also all
the subtrees of that eta-expandee (see SI-6673).

This commit adds a mechanism for fine-grained control over macro
expansion. Now it's possible to prohibit only the node, but not its
children from macro expanding.