implement + enable demos

c_os/user/PreemptiveLoopThread.cc

@@ -0,0 +1,17 @@
+#include "user/PreemptiveLoopThread.h"
+
+void PreemptiveLoopThread::run() {
+
+    /* Hier muss Code eingefuegt werden */
+
+    int cnt = 0;
+    while (true) {
+        // Basic synchronization by disabling PIT interrupts
+        cpu.disable_int();
+
+        kout.setpos(55, this->id);
+        kout << this->id << ": " << dec << cnt++ << endl;
+
+        cpu.enable_int();
+    }
+}