move battery status to 2nd row

requires less wide display
mavflightview: added --dualgps option
added more sophisticated readline command expansion
mavproxy_tracker: initial verison and antenna icons for map
mavproxy_map: Added support for antenna tracker icons in map
mavproxy_tracker: added support for tracker arm, disarm and level commands
mavflightview: better secondary GPS colours
raise version to 1.2.8