Improvements and fixes

[liveadmin]

- Some improvements have been done on admin panel internal operation.
- When an agent answers a chat session, root agent can see the chat screen. There was a bug in this area which has been fixed.
- Ability to invite a client to chat has added as an optional feature. It can be turned on in Configuration -> Chat Panel. Note that this may put some extra load on your site. Therefore disabled by default.
- Some versions of IE8 could not login to Admin panel. Fixed.
- Multiple issues in IE8 including black screen behind dialogs and ugly shadows fixed.
- There was a bug in chat transcripts (in log section), some not visible to agents. Fixed.