fix for

https://github.com/opencart/opencart/issues/448
fix for:

When turning on SEO Urls on a clean install of 1.5.5.1 I'm getting the following error when trying to go to the homepage.

Fatal error: Call to a member function query() on a non-object in *My Website*/public_html/catalog/controller/common/seo_url.php on line 74

Sorry if this is not a bug, but after looking around I could not find this mentioned anywhere else.

If it helps, I'm running PHP Version 5.3.19 with safe mode off.
Prevent direct access to http://.../system/logs/error.txt
Merge pull request #452 from rb2/patch-1

Prevent direct access to http://.../system/logs/error.txt
Send E-Mail Notification Admin  on Product Review
Merge pull request #460 from e-piksel/master

Send E-Mail Notification Admin on Product Review
added "New Review Alert Mail" status to setting mail tab.
Klarna: digest calculation is done in ASCII.
Merge pull request #463 from martynas-wm/master

Klarna update
refresh captcha of review form of product page when the form posted.

	i added rnd parameter to ensure refreshing.
Merge pull request #461 from hkulekci/opencart

added "New Review Alert Mail" status to setting mail tab.
Merge pull request #464 from hkulekci/patch-2

refresh captcha of review form of product page when the form posted.