Merge branch '2.x' into 3.0-unstable

* 2.x: (153 commits)
  Fix base_dir warning.
  Fix Pagination/search boolean checks, fixes #2141
  Add coveralls to readme
  Add .coveralls.yml
  Add Travis-CI config
  Fix for XML exports to escape & characters
  Move declaration of pods_mb_substr and pods_mb_strlen
  Tweak pods_mb_substr
  Tweak to pods_mb_strlen
  mb_substr and mb_strlen support for installs without it
  Remove markdown plugin headers causing issues with activations
  Readme update
  Fixes #2127
  Fix more preg_match issues with [^0-9]* which should be [^0-9]
  Quick hotfix for search data lookup
  Quick fix for #2125
  add Shelob9 to contributors list in readme
  Pods 2.4
  Corrected mixed up inline docs for pods_cache_get/ pods_cache_clear
  Renumber Pods 2.3.19 RC 1 to Pods 2.4 RC 1
  ...

Conflicts:
	.travis.yml
	README.md
	classes/Pods.php
	classes/PodsAPI.php
	classes/PodsAdmin.php
	classes/PodsData.php
	classes/PodsForm.php
	classes/PodsInit.php
	classes/PodsMeta.php
	classes/PodsMigrate.php
	classes/PodsUI.php
	classes/PodsView.php
	classes/fields/avatar.php
	classes/fields/boolean.php
	classes/fields/code.php
	classes/fields/color.php
	classes/fields/currency.php
	classes/fields/email.php
	classes/fields/file.php
	classes/fields/paragraph.php
	classes/fields/password.php
	classes/fields/phone.php
	classes/fields/pick.php
	classes/fields/text.php
	classes/fields/website.php
	classes/fields/wysiwyg.php
	classes/widgets/PodsWidgetList.php
	components/Markdown.php
	components/Migrate-Packages/ui/wizard.php
	components/Templates.php
	includes/classes.php
	includes/data.php
	includes/general.php
	includes/media.php
	init.php
	readme.txt
	ui/admin/help.php
	ui/admin/settings-tools.php
	ui/admin/setup-add.php
	ui/admin/setup-edit.php
	ui/admin/widgets/list.php
	ui/admin/widgets/single.php
	ui/fields/attachment.php
	ui/fields/media.php
	ui/fields/plupload.php
	ui/fields/select2.php
	ui/front/form.php
	ui/front/widgets.php
	ui/js/jquery.pods.attach.js