FIX DataDifferencer was trying to compare fields, even if the fields didn't exist causing an error.
Update Member.Email from 256 to 254 length

Fixes #3074
Adding .editorconfig file
BUG Fix versioned
Versioned is not writing Version to _version tables for subclasses of Version dataobjects which have their own DB fields
- Fix disjoint of ID / RecordID (which should be the same)
- Fix calculation of new record version
- Fix use of empty vs !isset to check for existing version

Conflicts:
	model/Versioned.php
	tests/model/VersionedTest.php

Cherry picked from commit c140459ac624738630ac8bec6a665fa3040e2e54
Merge pull request #3666 from Copperis/versioned-0-version-write-fix

Versioned now creates a new version if the version is 0
Add note about semvar to contributing.md
DOCS Repositioned house rules and added core commiter list.
MINOR Closing tag in Controller.ss
Merge pull request #3700 from dhensby/pulls/editor-config

Adding .editorconfig file
Merge pull request #3705 from JayDevlin/minor-controller-ss

MINOR Closing tag in Controller.ss
Merge pull request #3693 from JorisDebonnet/patch-4

Update Member.Email from 256 to 254 length
File.php: support for MS Office template / macro files

Fixes #3692
Add detection for PHP running in CGI mode and add HTTP_AUTHORIZATION rewrite rule
Detect and parse HTTP_AUTHORIZATION for basic authentication running PHP in CGI mode
Add comments about using CGI mode with Apache and Basic Auth in /docs/en/topics/environment-management.md
Added notes  to docs/en/changelogs/3.1.9.md
Merge pull request #3675 from micmania1/fix-datadifferencer-comparison

FIX DataDifferencer was trying to compare fields, even if the fields did...
Merge pull request #3708 from JorisDebonnet/patch-4

File.php: support for MS Office template / macro files
Merge pull request #3689 from guru-digital/patch-2

Add ability to use Basic Auth when running PHP in CGI mode in Apache
BUG Fix gridfield storing duplicate data in session
Merge pull request #3662 from camfindlay/corecommiters

DOCS Repositioned house rules and added core commiter list.
Merge pull request #3716 from tractorcow/pulls/3.1/fix-gridfield-session

BUG Fix gridfield storing duplicate data in session
ENHANCEMENT: Additional extension points for Tiny MCE editing, for when images are regenerated and manipulating the HTML prior to a save