The base for roster management (RosterEditWindow) has been made, and
adding new contacts works. Up next is contact removal and editing.
This leverages a new template (as defined in a protocol's
CayaProtocol::SettingsTemplate()), "roster," which should contain all
slots pertinent to editing/adding a contact member.
Two new API messages were added for this― IM_CONTACT_LIST_CONTACT_ADDED
and IM_CONTACT_LIST_CONTACT_REMOVED. The former will functionally just
be IM_CONTACT_INFO, but with some semantical meaning.
A new CayaMessage (CAYA_EDIT_ROSTER) was also added.
TemplateWindow was also edited to this end: Now, like RosterWindow/View,
it can be given a specific accounts' instance id, and it will prevent
the selection of another account. A new constructor was also added, to
allow a ProtocolTemplate to be explicitly passed to it― probably from
the program itself.