[Feature Request] Create random order number based on variable {randomstring}

[PhocaCz]

See: https://www.phoca.cz/forum/viewtopic.php?t=65339

Possible solutions:

• {randomstring} can be used together with another variables for having random order number
• database query can ask if created random string is not yet existing order number (in case only one variable will be used). This can prevent from duplicity of order number.