Merge pull request #8407 from kennyj/fix_profiler_comments

Fix wrong doc and message about rails profiler.
Override <%== to always behave as literal text rather than toggling based on whether escaping is enabled. Fixes that existing plaintext email templates using <%== unexpectedly flipped to *escaping* HTML when #8235 was merged.
Fix a typo in ActionController::Caching
Use send in Time marshal extensions since the methods are now private

See https://github.com/ruby/ruby/commit/9c1b3161f20162dc1682d758c0e4d2fc3a74745e

All Active Support tests pass in 2.0.0preview2 after this change.
Closes #8409
Merge pull request #8393 from frodsan/fix_dependend_order_test_example

Ensure original encoding does not change in mb_chars test.
Locate `=require turbolinks` at the bottom of application.js

Turbolinks should be located at the bottom of application.js
to detect assets change properly.
Merge pull request #8411 from YasuOza/turbolinks_require_bottom

Locate `=require turbolinks` at the bottom of application.js
Bump mailer to quiet the stdout log messages
style cleanup
Do not instantiate intermediate AR objects when eager loading.

Closes #3313
Merge pull request #8403 from senny/3313_after_find_is_triggered_too_often

Do not instantiate intermediate AR objects when eager loading.
Fixed issue where routes with globs caused constraints on that glob to
be ignored. A regular expression constraint gets overwritten when the
routes.rb file is processed. Changed the overwriting to an ||= instead
of an = assignment.
Track the default application.css/js files for turbolinks as per version 0.6.0
pg_namespace table isn't used.
Revert "Add documentation to TransactionIsolationError [ci skip]"

This reverts commit 5ff59704f68d284381606a1b76e4ffcfd73b2cfa.

Reason: Seems dubious and adds less value.

[ci skip]
Merge pull request #8416 from kennyj/redundant_pg_namespace

pg_namespace table isn't used.
copy edits [ci skip]
Updated 4.0 release notes

The release notes is changed to include only the major changes and point
to the changelogs for the complete list. This lets us talk more about the
features included in the upcoming release and make the guide more useful
and interesting than just a list of all changelogs.

This is still a WIP guide pending a lot of work.

[ci skip]
Merge branch 'master' of github.com:lifo/docrails

Conflicts:
	guides/source/migrations.md
Fix #8414. Performance problem with postgresql adapter primary_key function.