Improve Flash Uploader to generate random names during initial upload to filesystem

Flash uploader uses temporary folder to store uploaded files until user hits Save toolbar button. In that temporary folder files are named like this: uploader_flash_<control_number><file_number><original_file_name> This way, when 2 users select same file (same name) for upload on same edit page, then they are merged together and only one user will be able to use this file at the end.

I propose to generate temporary name for each uploaded file after file is uploaded to server (in OnUploadFile event) using "tempnam" php function and return it to js uploader part. Then, when user hits "Save", then js uploader will submit original file name and it's temporary name (does that already) so problem will be eliminated.

Also it may be a good idea to clean up "/system/tmp" folder after upload is made, so we don't store files, that were uploaded 1 day ago and were never used since then.