Update joomla.sql

Fix default value for the parameter guest_usergroup. This fix could be treated as security fix - if site has wrong value for the guest usergroup (13) and site already has the usergroup with such ID with administrator permissions - all of them would be administrators.
Update joomla.sql

Fix incorrect default value for guest_usergroup for PostgreSQL
Update joomla.sql

Fix incorrect default value for guest_usergroup for SQL Server
Add support for checking minimum PHP version in XML update stream

This introduces a <php_minimum> tag which should indicate the minimum supported PHP version of an extension
Optimize version_compare check, thanks @dongilbert
Add message if an update is available but unsupported
Install files
Update files
Restructure PHP version check
Merge remote-tracking branch 'joomla/staging' into phpUpdateLib
Filter images in JFormFieldImageList

Filter attribute has to be set before field is setup. Otherwise filter would not be used and there are all files from folder in a drop-down
Update imagelist.php

Corrected mistake
Update imagelist.php
[CODE STYLE] Corrected whitespace
Oops
Merge branch 'staging' into phpUpdateLib
Data object is a stdClass instance
Updating installation lang files: ar-AA, bg-BG, sw-KE, tr-TR
Add postinstall message informing of PHP version change in 3.3. Thanks
Michael Babker
Merge pull request #2802 from mbabker/phpUpdateLib

Add support for checking minimum PHP version in XML update stream