- fix ThreadSafeMessageBox always displays error icon
- allow to specify MSG_ERROR / MSG_WARNING or MSG_INFORMATION without a
custom caption / title
- allow to specify CClientUIInterface::ICON_ERROR / ICON_WARNING and
ICON_INFORMATION (which is default) as message box icon
- remove CClientUIInterface::OK from ThreadSafeMessageBox-calls, as
the OK button will be set as default, if none is specified
- prepend "Bitcoin - " to used captions
- rename BitcoinGUI::error() -> BitcoinGUI::message() and add function
documentation
- change all style parameters and enum flags to unsigned
- update code to use that new API
- update Client- and WalletModel to use new BitcoinGUI::message() and
rename the classes error() method into message()
- include the possibility to supply the wanted icon for messages from
Client- and WalletModel via "style" parameter