CustomMember extends wrong class.

CustomMember was extending the wrong class to be able to reference $this->owner.

Also, changed CustomMember to MyMemberExtension to remain consistent with the initial example.
BUG ArrayList failing to respect the SS_Sortable interface
ref: CWPBUG-133
BUG Fix access to protected Session::current_session()
Fixes #3144
Merge pull request #3138 from tractorcow/pulls/3.1/fix-arraylist-sorting

BUG ArrayList failing to respect the SS_Sortable interface
Merge pull request #3145 from tractorcow/pulls/3.1/fix-choose-stage

BUG Fix access to protected Session::current_session()
Merge pull request #3107 from micmania1/patch-1

CustomMember extends wrong class.
Update Zend_Locale_Format to the latest Zend version
Use php.internal_encoding instead of iconv.internal_encoding in PHP 5.6+
Update i18n.md

Corrected a mistake: to make a new locale available (in particular for use with silverstripe/translatable), i18n:common_locales needs to be updated, not i18n:common_languages.
Merge pull request #3158 from JorisDebonnet/patch-1

Update i18n.md
Merge pull request #3155 from simonwelsh/iconv_changes

Only use iconv.internal_encoding in PHP<5.6
Update simple-contact-form.md

corrects the description about the order of the arguments passed while creating Form object.
Merge pull request #3160 from sanjaymundhra/patch-8

Update simple-contact-form.md
Update sqlquery.md

adds missing datatype (i.e. Varchar) to the database field 'Name' of the Class 'Player'
Update DropdownField.php

An error in the example (missing comma) spotted by michaelcslweb
Merge pull request #3166 from phillprice/patch-2

Update DropdownField.php
Merge pull request #3165 from sanjaymundhra/patch-9

Update sqlquery.md
Remove redundant ternary expression

Replace it with casting to a boolean
Merge pull request #3174 from camspiers/patch-1

Remove redundant ternary expression
Merge branch '3.1' of https://github.com/silverstripe/silverstripe-framework into 3.1

# By Damian Mooyman (2) and others
# Via Simon Welsh (4) and others
* '3.1' of https://github.com/silverstripe/silverstripe-framework:
  Remove redundant ternary expression
  Update DropdownField.php
  Update sqlquery.md
  Update simple-contact-form.md
  Update i18n.md
  Use php.internal_encoding instead of iconv.internal_encoding in PHP 5.6+
  Update Zend_Locale_Format to the latest Zend version
  BUG Fix access to protected Session::current_session() Fixes #3144
  BUG ArrayList failing to respect the SS_Sortable interface ref: CWPBUG-133
  CustomMember extends wrong class.