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/VisionAPI.h

@@ -16,6 +16,8 @@
 #define DEFAULT_BORDER_SIZE 3            // VisionAPI.frcCreateImage
 #define DEFAULT_SATURATION_THRESHOLD 40  // TrackAPI.FindColor
 
+namespace frc {
+
 /* Forward Declare Data Structures */
 typedef struct FindEdgeOptions_struct FindEdgeOptions;
 typedef struct CircularEdgeReport_struct CircularEdgeReport;
@@ -174,3 +176,5 @@ int frcExtractColorPlanes(const Image* image, ColorMode mode, Image* plane1,
                           Image* plane2, Image* plane3);
 int frcExtractHuePlane(const Image* image, Image* huePlane);
 int frcExtractHuePlane(const Image* image, Image* huePlane, int minSaturation);
+
+}  // namespace frc