Added option to display highlight messages in server window

Modified Yaaic files:
/res/values/strings.xml - added "settings_highlight_notice_*" values in
Highlight
/res/values/settings.xml - added "*_highlight_notice" values for
Highlight options
/res/xml/preferences.xml - added CheckBoxPreference to Highlight options
/src/org/yaaic/irc/IRCConnection.java - added
service.getSettings().isHighlightMsgEnabled() and called it in relevant
methods
/src/org/yaaic/model/Settings.java - added method
isHighlightMsgEnabled()