BUGFIX: GridField delete icon now correctly deletes, rather than always just unlinking (Fixes 7801)

Fixes the handleAction function of GridFieldDeleteAction which wasn't differentiating between a 'deleterecord' action and an 'unlinkrelation' action.

Fixes http://open.silverstripe.org/ticket/7801
Merge pull request #732 from jcwacky/3.0

BUGFIX: GridField delete icon now correctly deletes, rather than always ...
BUG: Installer implies empty template used in tutorial

Have reworded the template options so that installers know that the
simple template is used for the tutorial
Merge pull request #733 from adrexia/installer

BUG: Installer implies empty template used in tutorial
BUG Restore tree children after updateNode() (fixes #7761)
Removed 'relation filters' from datamodel docs

Not implemented yet, so we shouldn't document it either
to avoid confusing devs. See #7595
API Reverse config extra statics control flow

Config system used to provide an add_static_source method, which was intended for
use by Extensions to add statics. But extensions for a class arent initialised
until at least one instance of that class is created, so before that the
Config system didnt include values from extensions

This patch reverses the control flow, so that the Config system explictly asks
each Object for its additional config sources via the new method
get_extra_config_sources. This method returns an array that can contain
string names of classes and also raw associative arrays.

The developer visible change is that Extension#add_to_class has been
deprecated. Instead there is a new method, get_extra_config, which has
the same method signature but needs to guarantee that it doesnt
cause side effects. Additionally there is no need to call
parent::get_extra_config - this is handled automatically.
Allow scheme-relative URLs in requirements

The Requirements class currently treats only absolute URLs as URLs, and
tries to interpret anything else as a filesystem path. This prevents
using scheme-relative URLs for requirements.

Example:
<% require javascript(//ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js) %>

This forces the unfortunate choice of not using a CDN for common
scripts, always using an https absolute URL, or accepting that some
browsers will throw a security warning when viewing the site in https.

This change allows scheme-relative URLs & updates RequirementsTest.
Merge pull request #735 from oddnoc/scheme-relative-requirements

Allow scheme-relative URLs in requirements
Added default sort to test data for better cross-db performance.
BUGFIX: Ensure that all_versions are sorted explicitly for better cross-db behaviour.
BUGFIX: Add double quotes to index columns for more reliable DB-schema management.
BUGFIX: Ensure that subtracting a sorted DataList works.
BUGFIX: Fix Versioned's stage_unique mode on PostgreSQL.
FIX Removes version checking for LSB in Object::static_lookup()

Late static binding was added in PHP 5.3, not 5.4. As such, the check for 5.4
and then fallback to Reflection isn't needed.
Updated translations
Merge pull request #734 from silverstripe-rebelalliance/trac/7799

API Reverse config extra statics control flow
i18n for "select an anchor" string (see #7798)
i18n for CMS section titles (see #7798)
i18n for GridField pagination footer (see #7798)