Working copy has been rolled back to pre 790 pull request. These now part of 1.5.5.2 branch.

Pull request 792/793 added manually as it was dropped by the revert.
Merge branch 'v1.5.5.1' of git://github.com/opencart/opencart.git into v1.5.6.1
Correct admin login validation
Merge pull request #892 from opencarthelp/v1.5.6.1

Admin login validation and redirect
Fixed issue #905: orders without shipping do not cause PHP notices.
Merge branch 'v1.5.6.1' of https://github.com/opencart/opencart into v1.5.6.1
Merge pull request #908 from martynas-wm/v1.5.6.1

PayPal PayFlow Iframe #905
Fix cart add missing argument 4 #910

http://forum.opencart.com/viewtopic.php?p=425505#p425505
Merge pull request #911 from ADDCreative/v1.5.6.1-patch1

Fix cart add missing argument 4 #910
Fixed SQL typo and added missing quote mark in setting model / update setting value method.
Code change as suggested in issue 898
Removed a lot of jQuery plugin example files, change logs and readme files. Any license files have been left in place.
Merge branch 'v1.5.6.1' of git://github.com/opencart/opencart.git into v1.5.6.1
Corrected typo of variable in response.php for render method.

Added header in the category no found conditional for 404.
Added correct headers when the not_found.tpl is triggered for catalog area; download, products, category, order, returns, cart, information, manufacturers.
Removed the 404 header when the cart is empty.
Merge branch 'v1.5.6.1' of git://github.com/opencart/opencart.git into v1.5.6.1
Removed check to accept the GNU GPL licence during install.
Removed private variable (unused) from step 1 install controller class.
Update pp_express_view.php