Cose style fixes.

Changes in theme adding/deleting processes, related DB structure changes.

Store all thumbnails under /system/thumbs/ folder

Need to cover all resized images as well (see associated discussion in Confluence).

Removed assignment by reference (=&), that was introduced in previous patch.

CS fixes

Changed grid configuration to use icons from core module.

The http://qa.in-portal.org/D8?id=120 diff was created using wrong command arc diff --update D8 instead of arc diff --update D8 --cl and that's why it doesn't contain any relevant changes.

Fixes.
Used more proper methods for escape/unescape request values.
Fiх to search logic, to allow keywords in URL without full search results recalculation.

Now numeric fields (int, float, double) won't have 0 stored in database, when an empty string value is submitted from the form.

Turns out this have negative side effect for numeric fields, where empty string is converted to 0 in database.