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/athena/include/Vision/ImageBase.h

@@ -12,6 +12,8 @@
 
 #define DEFAULT_BORDER_SIZE 3
 
+namespace frc {
+
 class ImageBase : public ErrorBase {
  public:
   explicit ImageBase(ImageType type);
@@ -24,3 +26,5 @@ class ImageBase : public ErrorBase {
  protected:
   Image* m_imaqImage;
 };
+
+}  // namespace frc