* Added a 'SYSTEM.SHOW_USER_LIST' field to the database.
* Incremented the database version to 265.
* Added 'RDSystem::showUserList()' and 'RDSystem::setShowUserList()'
methods in 'lib/rdsystem.cpp' and 'lib/rdsystem.h'.
* Added a 'Show User List in RDLogin' control to the 'Edit System'
dialog in 'rdadmin/edit_settings.cpp' and 'rdadmin/edit_settings.h'.
* Altered RDLogin to display a text input field for the user name
when 'Show User List in RDLogin' is unchecked.