Namespace all wpilibc functions/classes into "frc" namespace. (#311)

Base.h provides a backwards compatibility shim (enabled unless
NAMESPACED_WPILIB is defined) that does a "using namespace frc".
However, as some header files do not include Base.h, this may
be a breaking change in some corner cases (with an easy fix).

Fixes #218.

wpilibc/sim/include/simulation/MainNode.h

@@ -16,6 +16,8 @@
 
 using namespace gazebo;
 
+namespace frc {
+
 class MainNode {
  public:
   static MainNode* GetInstance() {
@@ -61,3 +63,5 @@ class MainNode {
     }
   }
 };
+
+}  // namespace frc

wpilibc/sim/include/simulation/SimContinuousOutput.h

@@ -21,6 +21,8 @@
 
 using namespace gazebo;
 
+namespace frc {
+
 class SimContinuousOutput {
  private:
   transport::PublisherPtr pub;
@@ -44,3 +46,5 @@ class SimContinuousOutput {
    */
   float Get();
 };
+
+}  // namespace frc

wpilibc/sim/include/simulation/SimDigitalInput.h

@@ -15,6 +15,8 @@
 
 using namespace gazebo;
 
+namespace frc {
+
 class SimDigitalInput {
  public:
   explicit SimDigitalInput(std::string topic);
@@ -29,3 +31,5 @@ class SimDigitalInput {
   transport::SubscriberPtr sub;
   void callback(const msgs::ConstBoolPtr& msg);
 };
+
+}  // namespace frc

wpilibc/sim/include/simulation/SimEncoder.h

@@ -16,6 +16,8 @@
 
 using namespace gazebo;
 
+namespace frc {
+
 class SimEncoder {
  public:
   explicit SimEncoder(std::string topic);
@@ -35,3 +37,5 @@ class SimEncoder {
   void positionCallback(const msgs::ConstFloat64Ptr& msg);
   void velocityCallback(const msgs::ConstFloat64Ptr& msg);
 };
+
+}  // namespace frc

wpilibc/sim/include/simulation/SimFloatInput.h

@@ -15,6 +15,8 @@
 
 using namespace gazebo;
 
+namespace frc {
+
 class SimFloatInput {
  public:
   explicit SimFloatInput(std::string topic);
@@ -29,3 +31,5 @@ class SimFloatInput {
   transport::SubscriberPtr sub;
   void callback(const msgs::ConstFloat64Ptr& msg);
 };
+
+}  // namespace frc

wpilibc/sim/include/simulation/SimGyro.h

@@ -15,6 +15,8 @@
 
 using namespace gazebo;
 
+namespace frc {
+
 class SimGyro {
  public:
   explicit SimGyro(std::string topic);
@@ -32,3 +34,5 @@ class SimGyro {
   void positionCallback(const msgs::ConstFloat64Ptr& msg);
   void velocityCallback(const msgs::ConstFloat64Ptr& msg);
 };
+
+}  // namespace frc