Added solution included on Forum osCommerce (http://forums.oscommerce.com/index.php?showtopic=281009) before publication of this version:

ERROR: invalid hash

Disabled checking of hash in phpThumb.config.php (parameter $PHPTHUMB_CONFIG['high_security_enabled'] set to false).
no image watermark
Fixed path of a watermark in catalog/includes/classes/oscThumb.php - line 231 looks like this:
$params .= "&fltr[]=wmi|/phpThumb/watermarks/".WATERMARK_IMAGE."(...)
no separator (pixel_trans.gif)
Assigned original separator in catalog/includes/functions/html_output.php (the change is shown in Installation Instructions section).

Other small changes:
- renamed section 'Thumbnails' at 'oscThumb'
- established a new order ID field in the database

Updated manual

NOTE: This version is prepared for a fresh installation of osCommerce 2.2RC2a.

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