Revert "Convert complex numbers to real numbers if imaginary part is floating-point 0.0."

This reverts commit 536a0ac50f.

Cf. <http://www.ginac.de/pipermail/ginac-devel/2014-January/002086.html/>.

src/complex/elem/cl_C_from_R_R_complex1.cc

@@ -17,7 +17,7 @@ const cl_N complex (const cl_R& a, const cl_R& b)
 {
 // Methode:
 // Falls b=0, nur a. sonst komplexe Zahl erzeugen.
-	if (zerop(b))
+	if (eq(b,0))
 		return a;
 	else
 		return allocate_complex(a,b);