Add Scheduler wireframe.

Right now does nothing but has containing classes for process and thread
information.

zion/scheduler/scheduler.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "scheduler/process.h"
+#include "scheduler/thread.h"
+
+namespace sched {
+
+// Create the scheduler object in a disabled state,
+// processes can be added but will not be scheduled.
+void InitScheduler();
+
+// Enables the scheduler such that processes will yield on ticks.
+void EnableScheduler();
+
+void Yield();
+
+// Scheduler will take ownership
+// of the created process.
+void InsertProcess(Process* proc);
+
+Process& CurrentProcess();
+Thread& CurrentThread();
+
+}  // namespace sched