BUG Don't sort when deleting records in ManyManyList::removeAll()

This breaks databases like MSSQL which don't allow an ORDER BY with
a subquery at the same time. DELETE queries don't need to be ordered,
so we can safely remove the default.
API: Move LimitWordCount() to Varchar
Update controller.md
Merge pull request #1719 from wilr/open5793

API: Move LimitWordCount() to Varchar
Fixed extra_requirements docs
Sync template-parser files

The template-parser files were not in sync, there were some lines added
in SSTemplateParser.php from 3334eafcb1c42b917dcafe46d87ea32f2b1014b8
and 0a9f3b75a9195092ff7c42265ec066339d8f8aa3 , I readded those parts
into the SSTemplateParser-include-file and recreated the
SSTemplateParser.php to get to a synced state...
Remove reference to /images/flush. 

Now a BuildTask. See /dev/tasks
FIX: Ensure FieldList::push() doesn't eliminate key
Merge pull request #1728 from wilr/open6445

FIX: Ensure FieldList::push() doesn't eliminate key
FIX: remove_extension should work on parameterized extensions
Merge pull request #1727 from wilr/open6079

FIX: remove_extension should work on parameterized extensions
API: Return a 404 error when no director rule is matched
API: add onBeforeRollback() and onAfterRollback() hooks.
Merge pull request #1730 from wilr/open5489

API: add onBeforeRollback() and onAfterRollback() hooks.
Merge pull request #1729 from ajshort/no-rule-match-404

API: Return a 404 error when no director rule is matched
Merge pull request #1725 from s-m/templater-parser-files-sync

Sync template-parser files
Fixed Versioned hook regression

Introduced by 5238e9cf48251f77f3fda095724990da3bee6803
API Replaced SSViewer.custom_theme with SSViewer.theme_enabled

Since we can't influence the setting of configuration values,
we also can't set/unset the 'custom_theme' value based on which
theme is set. This means the 'custom_theme' value goes stale,
and we can't rely on it e.g. in FilesystemPublisher.

The 'theme_enabled' toggle is a cleaner solution to the same problem,
since the 'custom_theme' was really just a way to remember the original
theme, while still disabling it. The toggle makes this more explicit,
but also requires users of the 'theme' setting to check for it.
FIX Config isolation in Director::test()