easy way of writing not implemented macros

Even though it's easy to mark regular method bodies as stubs (using ???),
there's no simple way of doing the same for macro methods. This patch
fixes the inconvenience.
Merge pull request #2497 from scalamacros/topic/macro-qqq

easy way of writing not implemented macros
SI-7464 allows FieldMirror.set to update vals

There's no reason to leave such sentinels in place inside a facility
designed to circumvent usual restrictions of static types / visibility.
Merge pull request #2504 from scalamacros/ticket/7464

SI-7464 allows FieldMirror.set to update vals
[nomaster] unbreaks test.bc

The optimizer behaves unexpectedly smartly, stripping off unused private
methods. Unfortunately, sometimes private methods might be compiled down
to public Java methods, so stripping them off might lead to binary
incompatibilities.

This particular commit recovers from this problem caused by
https://github.com/scala/scala/commit/5e715396af.
Merge pull request #2550 from scalamacros/2.10.x

[nomaster] unbreaks test.bc
Prevent slash duplication.

Don't add trailing slash to external doc URL if it already ends with
one.