Disallow usernames with less than 3 characters

cf. WoltLab/WCF#1144
Remove obsolete ENCRYPTION_* options
Disallow usernames with more than 255 characters

SQLSTATE[22001]: String data, right truncated: 1406 Data too long for column 'username' at row 1
Added option type for user option selection
Fixed quit function
Added user quit cronjob
Fixed icon size
Added link to avatar edit form
Style optimizations
Fixed signature issue
Fix Non-static method wcf\system\user\authentication\UserAuthenticationFactory::getUserAuthentication()
Add github integration
Throw NamedUserException on error
Fix comment
Merge branch 'master' into 3rdAuth
Add Twitter integration
Fixed broken links
Added max length for "about me"
Merge branch 'master' into 3rdAuth
Add facebook integration