Use the correct variable as the key into $record

It was using $fieldName, which is the CSV field name, not the database
field name. This prevents duplicate detection from working. It now
properly uses $SQL_fieldName
Merge pull request #1821 from oddnoc/csvbulkloader-findexisting-2.4

Use the correct variable as the key into $record
composer/installer dep workaround

Moved to end of requirements, to work around a bug in composer - see https://github.com/composer/composer/issues/1147. This caused the dependencies to be installed in the wrong folder because the custom 'silverstripe-module' instructions hadn't been loaded at the time the core modules were installed via composer.
FIX: Falling back to summaryFields() should skip non database fields.
Have 'Configuration Reference' link point to uploadfield page

Oops.
BUG Fixes issue with '+' characters in url.
Partial code formatting / phpdoc cleanup of Versioned
Fix typo in templates documentation
Fixing array to string conversion in dev/build for PHP 5.4
Bugfix: Added private static $defaultFormat in order to choose default via config. Permit WCAG validation of XHTML.
Fix file link recognition in HtmlEditorField.js

The new file_link format ([file_link,id=\d+]) uses a comma which was not reflected in the regex.
Recursive folder creation in Upload
FIX Avoid unnecessary user_error when no controller set for friendly errors in Debug class
Updating docs to use SiteTree for aggregates with LastEdited example

Using SiteTree is faster, because it doesn't do any joining of Page
to get the aggregate, even though the LastEdited field is only on
SiteTree in the case of Page.
Merge pull request #1944 from patbolo/bugfix/debug-no-controller

FIX Avoid unnecessary user_error when no controller set for friendly err...
Added "saves into..." label to UploadField template

CMS users shouldn't need to guess where their files will end up.
Merge pull request #1940 from chillu/pulls/uploadfield-folder-label

Added "saves into..." label to UploadField template
Merge pull request #1939 from chillu/pulls/folder-creation

Recursive folder creation in Upload
FIX: If CSV column mapping maps to function, keep key value as key.

Fixes http://open.silverstripe.org/ticket/6473

When using CSVParser::$columnMapping to map columns to a callback action, it previously used the action name as the key value. This prevented users from defining multiple entries to the same callback. This patch retains those key values and simply runs the callback field name filter later on.
Code formatting / PHPDoc cleanup