FIX: Image resizing breaks when one of the resized image dimensions is between 0 and 1.
Solution: Round up to 1 instead of down to 0.
Converted php errors to exceptions in the process.
Correct regression around ?flush

?flush used to work. There's no reason why it shouldn't.
Merge pull request #3593 from simonwelsh/patch-1

Correct regression around ?flush
Merge pull request #3591 from jedateach/issues/image-resize-fix

FIX: Image resizing breaks when one of the resized image dimensions is between 0 and 1
Update Requirements.php

Makes requirements inclusion work with old PCRE versions
Merge pull request #3594 from jdemeschew/patch-1

Makes requirements inclusion work with old PCRE versions.
Bugfix NumericField shows (none) for 0 on readonly
Merge pull request #3553 from nhorstmeier/NumericReadonlyField

Bugfix NumericField shows (none) for 0 on readonly
Fix whitespace issues in NumericField/NumericFieldTest
Update versioning.md

Added information about $SilverStripeNavigator
Update versioning.md
Merge pull request #3606 from g4b0/patch-5

Update versioning.md
Explicit cast return of DBField->exists()
Update translations
Add changelogs for 3.1.7-rc1
Added 3.1.7-rc1 changelog
Update DataObject.php

Documentation fix:

Table at http://api.silverstripe.org/3.1/class-DataObject.html is displaying the data wrong. Current it says "protected A" instead of "protected ValidationResult" as it should be.
Merge pull request #3613 from spekulatius/patch-1

Update DataObject.php
Update HtmlEditorConfig::enablePlugins() to return instance
Filter heading being processed as part of code

Whitespace issue causing the filter header to become part of the sorting example above - fixed whitespace.