QuickStart examples: shorten var names, remove superfluous 'using'.

doc/examples/QuickStart_example.cpp

diff --git a/doc/examples/QuickStart_example.cpp b/doc/examples/QuickStart_example.cpp
index 3fbd6fa..f4ab2fb 100644
--- a/doc/examples/QuickStart_example.cpp
+++ b/doc/examples/QuickStart_example.cpp
@@ -2,7 +2,6 @@
 #include <Eigen/Dense>
 
 using Eigen::MatrixXd;
-using Eigen::VectorXd;
 
 int main(int, char *[])
 {
@@ -11,5 +10,5 @@
   m(1,0) = 2.5;
   m(0,1) = -1;
   m(1,1) = m(1,0) + m(0,1);
-  std::cout << 2*m << std::endl;
+  std::cout << m << std::endl;
 }

doc/examples/QuickStart_example2_dynamic.cpp

diff --git a/doc/examples/QuickStart_example2_dynamic.cpp b/doc/examples/QuickStart_example2_dynamic.cpp
index c304c93..b46ecef 100644
--- a/doc/examples/QuickStart_example2_dynamic.cpp
+++ b/doc/examples/QuickStart_example2_dynamic.cpp
@@ -7,9 +7,9 @@
 int main(int, char *[])
 {
   MatrixXd m(3,3);
-  for (int rowIndex = 0; rowIndex < 3; ++rowIndex)
-    for (int columnIndex = 0; columnIndex < 3; ++columnIndex)
-      m(rowIndex, columnIndex) = rowIndex + 0.01 * columnIndex;
+  for (int row = 0; row < 3; ++row)
+    for (int column = 0; column < 3; ++column)
+      m(row, column) = row + 0.01 * column;
   VectorXd v = VectorXd::Ones(3);
   std::cout << m * v << std::endl;
 }

doc/examples/QuickStart_example2_fixed.cpp

diff --git a/doc/examples/QuickStart_example2_fixed.cpp b/doc/examples/QuickStart_example2_fixed.cpp
index 6d7d63d..9fcddcd 100644
--- a/doc/examples/QuickStart_example2_fixed.cpp
+++ b/doc/examples/QuickStart_example2_fixed.cpp
@@ -7,9 +7,9 @@
 int main(int, char *[])
 {
   Matrix3d m;
-  for (int rowIndex = 0; rowIndex < 3; ++rowIndex)
-    for (int columnIndex = 0; columnIndex < 3; ++columnIndex)
-      m(rowIndex, columnIndex) = rowIndex + 0.01 * columnIndex;
+  for (int row = 0; row < 3; ++row)
+    for (int column = 0; column < 3; ++column)
+      m(row, column) = row + 0.01 * column;
   Vector3d v = Vector3d::Ones();
   std::cout << m * v << std::endl;
 }