BA: improve turtling more

reduce turtling slightly (65 to 60)
add an off-map or within another base check for limb positions and reposition if necessary. base the off-map check on a larger radius than the size itself, so that extra retarded rear guard positions don't come up.
make new organs merge into a based turtle if a turtle with a single organ is within twice the base distance or outpost distance. cause basing to change the turtle's position to an average of its organs positions
use factory missing defense modifier for any undefended limb