as an extension of #2831
The validation of PARAM_ALPHANUM in source:elgg/trunk/profile/index.php prevents dino users with underscores in their username being able to access or create their profiles. The change to PARAM_SAFEDIR (which is the same as ALPHANUM + underscore and hyphen) needs to be made to all the php files in that same directory. Also, source:elgg/trunk/.htaccess needs to be updated to the same regex used in r150 so that DINO usernames in the pretty url get redirected properly.