[Users] Correction to McLachlan dot[A] advection terms

[Erik Schnetter]

I found that the dot[A] advection terms in McLachlan were not
implemented correctly. In particular, Kerr-Schild black holes were not
manifestly stationary. I corrected this, and pushed the changes.

Most BSSN evolutions don't use A as evolved variable (A is
approximately equivalent to dot[alpha]), and are thus not affected.

-erik

-- 
Erik Schnetter <schnetter at cct.lsu.edu>   http://www.cct.lsu.edu/~eschnett/