DOCS Repositioned house rules and added core commiter list.
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
Merge pull request #3721 from gordonbanderson/TINY_MCE_EDIT_EXTENSION_POINTS

ENHANCEMENT: Additional extension points when editing with Tiny MCE
FIX: GD - check file exists before getimagesize

Use is_readable to check the file exists and is readable
Merge pull request #3726 from willmorgan/bugfixes/gd-image-exists

FIX: GD - check file exists before getimagesize
Restructure of the docs markdown source files into more logical taxonomy.
Rebased on 3.1
Add readme to include status of docs rewrite and high level todos

Conflicts:
	docs/en/03_Upgrading.md
	docs/en/03_Upgrading/00_Upgrading.md
	docs/en/03_Upgrading/index.md
Update documentation introduction
Move todo list to trello.
Add introduction files to each of the sections
Review and tidy up contributing documentation.
Review, clean up of CLI documentation
Review, cleanup and refresh of integration section
Review email documentation
Tidy up templates guide
Clean up debugging documentation
Review and rewrites for Testing Developer Guide