Changed optimization for one function

OptimalAlignment::weightedAlignment crashed with intel c++ -O3.
I was not able to find why (gdb and valgrind did not help).
With this workaround, that function only is optimized at -O2 anyway.

src/tools/OptimalAlignment.cpp

@@ -110,6 +110,10 @@ double OptimalAlignment::calculate(bool squared, std::vector<Vector> & derivativ
 
 	return err;
 }
+
+#ifdef __INTEL_COMPILER
+#pragma intel optimization_level 2
+#endif
 /// this does the weighed alignment if the vector of alignment is different from displacement
 double OptimalAlignment::weightedAlignment( bool rmsd){
 	double tmp0,tmp1,walign,wdisplace,const1,ret;