Merge 2.10 to 2.11

Three `[backport]` commits (and their merge commits) are merged using `-s ours`.

```
lucmac:scala luc$ git lg
*   c66b886 - (HEAD, upstream/2.11.x, upstream-writable/2.11.x, origin/2.11.x, 2.11.x) Merge pull request #3952 from gourlaysama/wip/t8828-lint-innacessible (4 hours ago) <Grzegorz Kossakowski>

lucmac:scala luc$ git checkout -b merge/2.10-to-2.11-sept-2
lucmac:scala luc$ export MB=$(git merge-base head origin/2.10.x)
lucmac:scala luc$ git log --graph --oneline --decorate $MB..origin/2.10.x
*   d2a5555 (upstream/2.10.x, upstream-writable/2.10.x, origin/2.10.x, 2.10.x) Merge pull request #3937 from som-snytt/issue/8787-doc-backport
|\  
| * 8876227 (som-snytt/issue/8787-doc-backport) [backport] SI-8787 Backport Regex doc
|/  
*   1d3613b Merge pull request #3865 from xeno-by/topic/extractor-macros-210x
|\  
| * 36379cf [backport] transformers no longer ignore UnApply.fun
*   ac7e102 Merge pull request #3860 from gourlaysama/wip/t7710-backport
|\  
| * fceae70 [backport] SI-7710 fix memory performance of RegexParsers in jdk7u6+
*   b5759ef Merge pull request #3904 from kzys/jira-8314-2.10.x
|\  
| * b6c00d6 Prevent SI-8314 by adding a test
|/  
* d74da16 Merge pull request #3752 from jeroentervoorde/SI_8589
* 099a426 SI-8589 Performance improvement for ArrayCharSequence.toString

lucmac:scala luc$ git merge b5759ef
Auto-merging src/library/scala/runtime/SeqCharSequence.scala
warning: inexact rename detection was skipped due to too many files.
warning: you may want to set your merge.renamelimit variable to at least 2183 and retry the command.
Merge made by the 'recursive' strategy.
 src/library/scala/runtime/SeqCharSequence.scala |  7 ++++++-
 test/scaladoc/run/t8314.check                   |  3 +++
 test/scaladoc/run/t8314.scala                   | 16 ++++++++++++++++
 3 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 test/scaladoc/run/t8314.check
 create mode 100644 test/scaladoc/run/t8314.scala

lucmac:scala luc$ git lg
*   3f69314 - (HEAD, merge/2.10-to-2.11-sept-2) Merge commit 'b5759ef' into merge/2.10-to-2.11-sept-2 (21 seconds ago) <Lukas Rytz>
|\  
| *   b5759ef - Merge pull request #3904 from kzys/jira-8314-2.10.x (4 weeks ago) <Grzegorz Kossakowski>
| |\  
| | * b6c00d6 - Prevent SI-8314 by adding a test (5 weeks ago) <Kato Kazuyoshi>
| |/  
| *   d74da16 - Merge pull request #3752 from jeroentervoorde/SI_8589 (9 weeks ago) <Adriaan Moors>
| |\  
| | * 099a426 - SI-8589 Performance improvement for ArrayCharSequence.toString (3 months ago) <Jeroen ter Voorde>
| |/  
* |   c66b886 - (upstream/2.11.x, upstream-writable/2.11.x, origin/2.11.x, 2.11.x) Merge pull request #3952 from gourlaysama/wip/t8828-lint-innacessible (4 hours ago) <Grzegorz Kossakowski>

lucmac:scala luc$ git merge 2.10.x -s ours
Merge made by the 'ours' strategy.

lucmac:scala luc$ git df 3f69314
lucmac:scala luc$ 
```