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/Resource.h

@@ -16,6 +16,8 @@
 #include "ErrorBase.h"
 #include "HAL/cpp/priority_mutex.h"
 
+namespace frc {
+
 /**
  * The Resource class is a convenient way to track allocated resources.
  * It tracks them as indicies in the range [0 .. elements - 1].
@@ -45,3 +47,5 @@ class Resource : public ErrorBase {
 
   static priority_recursive_mutex m_createLock;
 };
+
+}  // namespace frc