Add regression test for issue #66 (ComplexSchur of zero matrix).

test/eigensolver_complex.cpp

diff --git a/test/eigensolver_complex.cpp b/test/eigensolver_complex.cpp
index 38ede7c..e1ce575 100644
--- a/test/eigensolver_complex.cpp
+++ b/test/eigensolver_complex.cpp
@@ -49,6 +49,10 @@
   ComplexEigenSolver<MatrixType> ei1(a);
   VERIFY_IS_APPROX(a * ei1.eigenvectors(), ei1.eigenvectors() * ei1.eigenvalues().asDiagonal());
 
+  // Regression test for issue #66
+  MatrixType z = MatrixType::Zero(rows,cols);
+  ComplexEigenSolver<MatrixType> eiz(z);
+  VERIFY((eiz.eigenvalues().cwise()==0).all());
 }
 
 void test_eigensolver_complex()
@@ -58,4 +62,3 @@
     CALL_SUBTEST( eigensolver(MatrixXcd(14,14)) );
   }
 }
-