Forum: simplified the registration for new members

[Liviu Lalescu]

This is my second attempt to simplify the registration for new users. I added another simpler verification question (in English, unfortunately it seems it cannot be translated, but I will try some more).

[Liviu Lalescu]

It can be translated, but all the translations will be shown. I hope this is a good solution. The future SMF (forum) 2.1 will have only one translation shown for the verification question, but it is now still unstable, not recommended for production use.