BUG Load just one of each plugin.
Merge pull request #3040 from mateusz/plugins30

BUG Load just one of each plugin.
FIX: ConfirmedPasswordField used to expose existing hash
Merge pull request #3044 from mateusz/hash

FIX: ConfirmedPasswordField used to expose existing hash
Oembed warning if GD function is missing

Silencing errors from a function is terrible so I've stopped that.

I've also added detection for if `imagecreatefromstring` is a declared function and a useful error is thrown if not
API Make default gridfield paging configurable
Documentation improved
DOCS: Minor fixes to RestfulService documentation
Merge pull request #3026 from tractorcow/pulls/3.1-gridfield-paging

API Make default gridfield paging configurable
Fixed config setting link
Merge pull request #3076 from martinduparc/patch-4

Fixed config setting link
BUG Fix ImageTest
Image test would erroneously reset the Image::$backend to null if the test was skipped, breaking subsequent test cases
API Injector supports nesting
BUG Resolve issue with DirectorTest breaking RequestProcessor
Injector::nest and Injector::unnest are introduced to better support sandboxing of testings.
Injector and Config ::nest and ::unnest support chaining
Test cases for both Injector::nest and Config::nest
Merge pull request #3068 from kinglozzer/patch-1

DOCS: Minor fixes to RestfulService documentation
BUG HTMLText whitelist considers text nodes
Minor improvement to #2853.
If a list of whitelisted elements are specified, text nodes no longer evade the whitelist
Removed demo folder
BUG Fix jstree when duplicating subtrees
Merge pull request #3031 from tractorcow/pulls/3.1-fix-tree-duplication

BUG Fix jstree when duplicating subtrees
Merge pull request #3078 from tractorcow/pulls/3.1-remove-thirdparty-demo

Removed demo folder
Merge pull request #3077 from tractorcow/pulls/fix-imagetest

BUG Fix ImageTest
Fix 'Uncaught ReferenceError: jQuery is not defined' if jQuery is not included in template.