Rename squares_aligned()

Rename to the shorter but still
clear aligned()

No functional change.

src/search.cpp

@@ -1331,7 +1331,7 @@ moves_loop: // When in check and at SpNode search starts from here
     // We exclude the trivial case where a sliding piece does in two moves what
     // it could do in one move: eg. Ra1a2, Ra2a3.
     if (    m2to == m1from
-        || (m1to == m2from && !squares_aligned(m1from, m2from, m2to)))
+        || (m1to == m2from && !aligned(m1from, m2from, m2to)))
         return true;
 
     // Second one moves through the square vacated by first one