Eliminate the C FFI; Namespace lib API and DeviceManager

We decided to get rid of the C FFI for libs. It was becoming too intricate
and complicated. It was becoming a technical burden and expanding into
too much extra code. It's unfortunate, but we'll have to give up on getting
out-of-tree hot-loadable libraries the easy way.

It's possible to still do it with cross compilation or by keeping track
of the libstdc++ version that the running harikoff binary was compiled
against. Then we can ensure that our loadable lib code is linked against
that same libstdc++ code and this should ensure ABI stability.

hcore/include/deviceManager/deviceManager.h

@@ -9,6 +9,9 @@
 #include <iostream>
 #include <user/senseDeviceSpec.h>
 
+namespace hk {
+namespace device {
+
 class DeviceManager
 {
 public:
@@ -39,4 +42,7 @@ public:
         senseDeviceSpecs;
 };
 
+} // namespace device
+} // namespace hk
+
 #endif // DEVICEMANAGER_H