SI-8013 Nowarn on macro str interpolation

When warning about stray "foo $bar" under `-Xlint`,
which may be missing an interpolator id, suppress
the warning if we're in the middle of a macro
expansion, since we have no useful heuristic to
apply to the expanded tree.

The test for whether the string is part of an
expanded tree is to check all open macros for
an expanded tree that contains the literal tree
under scrutiny. (This is deemed more paranoid
than looking for a macro application that is an
enclosing position.)
add method dequeueOption to immutable.Queue

This allows immutable.Queue to be used conveniently in functional code.
Method is in the spirit of `headOption` on seqs or `get` on maps. Also
adds a unit test for immutable.Queue.
Merge pull request #3191 from retronym/ticket/deprecate-par-view

Remove parallel collection views and, with them, Gen*View
Merge pull request #3228 from retronym/merge/2.10.x-and-pr-3209-to-master

Merge #3209 and 2.10.x to master
undeprecates c.parse

We never thought that c.parse is going to be completely subsumed by
quasiquotes, but hoped that the use cases that are going to be lost
aren’t going to be noticed by anyone.

Unfortunately, this isn’t the case, so I’m undeprecating c.parse until
we get a better story for those for whom quasiquotes are not enough.
Merge pull request #3231 from xeno-by/topic/undeprecate-parse

undeprecates c.parse
Merge pull request #3225 from som-snytt/issue/8013-interp-nowarn

SI-8013 Nowarn on macro str interpolation
Merge pull request #3226 from ziggystar/patch-1

add method dequeueOption to immutable.Queue
SI-8046 Fix baseTypeSeq in presence of type aliases
Pending test for SI-6161

Not solved with base type dealiasing
SI-8046 Only use fast TypeRef#baseTypeSeq with concrete base types

We can only compute the base type sequence (BTS) of a `TypeRef` by
element-wise transforming the BTS of the referenced symbol if
there are no abstract types in its BTS type symbols.

In the now-working test case, `pos/t8046.scala`, the difference
between the old and new calculation of the BTS is:

    this                 = Three.this.Alias[Int]
    sym.info.baseTypeSeq = BTS(One.this.Op[A],Any)
    mapped BTS           = BTS(Three.this.Op[Int],Any)
    full BTS             = BTS(Three.this.Op[A],A => A,Object,Any)