Uppercase BB-codes are not supported

Step to reproduce:

1. Sign In, Open Create topic screen
2. Input message with BB-code written in uppercase (for ex: [B]Insert your text here[/B]) and save the topic

ActualResult: BB-code is not applied, text [B]Insert your text here[/B] is shown
ExpectedResult: BB-code applied (in our example bold text is shown, without [B])