Update datamodel.md to use an array argument to Enum instead of the more error-prone string

The previous argument to the Enum was: 
"Status" => "Enum('Active, Injured, Retired')"

This would cause issues where the 'Injured' and 'Retired' statuses would actually be stored in the database as ' Injured' and ' Retired' respectively, at least in 3.0.

Using an array() to specify the enum, and using normal array syntax (albeit within a string) is less likely to cause errors.
fixed wrong ID output for many_many and has_many relations
FIX gridfield delete alert selector specificity
Updated Te Reo translation
API: Pass extra context information to shortcode handlers.

This allows shortcodes to perform more complex actions on the element
which contains them. For example, the element reference can be used
to add extra classes or attributes to links which provide additional
metadata.
Merge pull request #2507 from ajshort/pull-3

API: Pass extra context information to shortcode handlers.
Merge pull request #2502 from colymba/fix-gridfield-delete-alert

FIX gridfield delete alert selector specificity
Unit test coverage for CMSMenuItem
Unit tests for Email

It's not much, but it's a start
BUG: Fix CMS forms with validation errors responding incorrectly.

A new form instance was being constructed for the response, which mean
that a lot of the validation information was lost. This fix means that:

* Enterered data is correctly persisted.
* A validation error notification is displayed.
FIX: Fix not switching to the correct tab on validation error.
Merge pull request #2514 from ajshort/pull-4

CMS Validation
Merge pull request #2510 from kinglozzer/cmsmenuitem-tests

Unit test coverage for CMSMenuItem
Appending to debug.log file

Until now debug.log files were loaded into memory, concatenated and then re-written to disk. This is an intensive operation on a large file.

I've added the `FILE_APPEND` flag to append to this file instead.
No HTML entities in "Groups" ListboxField (fixes #2513)
Merge pull request #2518 from dhensby/patch-1

Appending to debug.log file
Removed accidental artifacts
Remove large left margin on field description within cms-content-tools
Merge pull request #2511 from kinglozzer/email-tests

Unit tests for Email class
Merge pull request #2498 from jkempff/fix-1

fixed wrong ID output for many_many and has_many relations