Fix SI-7224.

Don't focus positions assigned to the TypeTree of a parent of a Template
when the parent exists in the source. A focused position (instance
of `OffsetPosition`) makes it invisible to the presentation compiler
when it looks for the innermost enclosing tree of a given position
(breaking hyperlinking, for example).
Merge pull request #2212 from dragos/fix/SI-7224

Fix SI-7224.
SI-5710 has fixed itself

My job here is only to submit tests.
reifier is now aware of SI-7235

SI-7235 is caused by a long-standing todo in typedRefinement, which leads
to originals of compound type trees swallowing their stats.

I'm not sure how exactly to fix SI-7235, but what I am sure about is that
we shouldn't silently discard stats during reification. This patch
introduces a new implementation restrictions, which now reports that
reify of compound type trees with non-empty stats isn't going to work.
SI-7234 Make named args play nice with dep. method types

Some care is needed to avoid interaction with constant
types (e.g pos/z1730.scala) and with existentials
(e.g. t3507-old.scala).
SI-7226 Fix inference regression caused by TypeVar equality.

TypeVars, being mutable creatures, mustn't have structural
equality/hashing, otherwise TypeRefs that differ only by
having distinct TypeVars as components get wrongly uniqued
together.

The reported bug showed the disaterous consequences: constraints
from the `C?[Int]` in the return type applied to the `?C[?A]` in
the parameter list.

This commit overrides `equals` and `hashCode` in `TypeVar`
to use reference equality. An alternative fix would be to drop
the `case`-ness of the class, as was the case before 0cde930b
when this regressed.
SI-7328 Bail out of names/defaults if args are error typed

To avoid a crasher later on with a null type inside a
sequence argument.
Merge pull request #2228 from retronym/ticket/7226

SI-7226 Fix inference regression caused by TypeVar equality
Merge pull request #2223 from scalamacros/ticket/7235

reifier is now aware of SI-7235
Merge pull request #2221 from scalamacros/ticket/5710

SI-5710 has fixed itself
Merge pull request #2225 from retronym/ticket/7234

SI-7234 Make named args play nice with dep. method types
Merge pull request #2224 from retronym/ticket/7238

SI-7328 Bail out of names/defaults when args are error typed
Merge 2.10.x into master

Conflicts:
	src/compiler/scala/tools/nsc/typechecker/Typers.scala
Merge 2.10.x into master

Conflicts:
	src/compiler/scala/reflect/reify/Errors.scala
	src/compiler/scala/tools/nsc/typechecker/NamesDefaults.scala
Merge pull request #2242 from adriaanm/merge-2.10.x

Merge 2.10.x into master