Smooth markers tweaks

[Bubbus]

A few changes around the 'smooth markers':

• Now even smoother for other squads and vehicles (uses getPosVisual/getDirVisual).
• Fixed markers not appearing in the GPS when aircraft exist in the mission (or are zeused into the mission).
• Minor improvement to marker appearance in the GPS view.
• Smooth markers now respect the ca_specialistMarkerClasses array.
• Added f_var_smoothFTMarkers_hide to the initServer options so map-markers can be totally turned off in smooth-marker mode.
• Improved marker behaviour when units and leaders die.

Tested locally and did a server testing session, behaviour should now be quite consistent with the normal markers.