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/shared/include/CircularBuffer.inc

@@ -9,6 +9,8 @@
 
 #include <algorithm>
 
+namespace frc {
+
 template <class T>
 CircularBuffer<T>::CircularBuffer(size_t size) : m_data(size, 0) {}
 
@@ -183,3 +185,5 @@ size_t CircularBuffer<T>::ModuloDec(size_t index) {
     return index - 1;
   }
 }
+
+}  // namespace frc