Mahara 15.10.4

* Bug 1508684: Unserialize untrusted data when importing skins
 * Bug 1555410: unread email icon in the banner display wrong
 * Bug 1563143: Breakage around dropzone error hander callbacks
 * Bug 1576643: TinyMCE is not available on the iPad
 * Bug 1577259: PHP7 fixing dwoo dynamic property references
 * Bug 1578995: In the skin module the background position of the image cannot be translated
 * Bug 1579628: Modern theme: disappearing password label
 * Bug 1579999: PHP Fatal error: Class 'Session' not found
 * Bug 1580399: Users can login to suspended institutions via external auth under some circumstances
 * Bug 1582778: Japanese text jumbled when submitted with image
 * Bug 1582934: Navigation not entirely / not visible on iPad
 * Bug 1587474: No indents forum reply fails when the last post has been deleted
 * Bug 1588613: Mahara not respecting session lifetime setting from admin config page
 * Bug 1591782: Default theme breaks with skin background
 * Bug 1592213: Render issue with Masonry on Skins page
 * Bug 1592236: Sessions: constantly asked to log in to access the Users Admin screen
 * Bug 1596755: Ocean theme - tabbing through unselected sub-menu items
 * Bug 1599305: $USER->get('grouproles') returning values for deleted groups
 * Bug 1084336: mnet: mahara doesn't implement kill_child which results in not being logged out when logged out from a remote IdP over mnet
 * Bug 1234615: Not checking artefact permissions before exporting
 * Bug 1354222: Files within a group aren't deleted after deleting the group
 * Bug 1530702: New messages in inbox aren't displayed in bold in "Inbox" block
 * Bug 1545375: Button border missing when no second button in web services application connections
 * Bug 1548522: Avatars overlap in friends block
 * Bug 1558246: Shared collections in a group don't display for the admins
 * Bug 1577258: More PHP7 compatibility problems with function parameters
 * Bug 1578512: Escape filenames with quotes in them, in Content-Disposition:attachment headers
 * Bug 1582039: Submitted portfolios don't appear in group pages block automatically
 * Bug 1582472: No moving of long blocks
 * Bug 1582989: Make top line on "Edit" button more visible on certain pages
 * Bug 1588091: StudentID not displayed in content
 * Bug 1588599: PHP 7 unrecoverable errors in 16.04
 * Bug 1592276: Still SSRF vulnerability in external feed
 * Bug 1598974: Mahara as MNet IDP breaks because of longer session ids
 * Bug 1600069: See other's profile images one is not meant to
 * Bug 1581227: PHP Fatal error: Call to undefined function log_()
 * Bug 1582967: Comment deletion forms & buttons with non-unique IDs
 * Bug 1599404: The function "get_mahara_install_subdirectory" doesn't correctly handle a URL with a missing trailing slash
 * Bug 1583435: Make it easier to run one specific feature file
 * Bug 1600668: Google drive folders no longer work in Google Apps block
 * Bug 1537908: Warnings when LDAP server is not available