tasdrive now only monitors motors which are driving.

Fixes SICS-568 Because tasdrive now stops calling status checking on a
motor which has terminated for any reason.
SICS-570: The correct motor names are now reported by tasdrive.
SICS-575: Use ANSTO motor names when reporting limit violations.

tasub.h

@@ -29,6 +29,8 @@
                 int mustDrive; 
                 int mustDriveQ;
                 pMotor motors[12];
+                char motname[12][32];
+                int busy[12];
                 tasReflection r1, r2;
                 int ubValid;
                 int silent;