videochat modifications

All about just dolphin 7 videochat:

- Hide (unvisible) admins option: users cannot see admins name in namelist tab (admin can turn on / off uvisible status)

- Last 15-20 messages visible when an user enter to a room (more easy to know what is the actual story there...)

- Ban video and voice option: moderators can turn off users camera and / or voice

- When an user logging in with desktop application chat window starting (not the friends and members list)

- Users not authorized to set font styles under chat setting, just Admin can change it under administration (this admin option OK like it is right now in admin panel, I do not care about font style, the font size is enough)

- Users can set "who can view my camera" - (everybody, just friends, nobody) or just turn off/on viewers one by one