Separate kernel code from test code

Eventually I want the kernel to be loaded from the SD card as well, but
it still needs to separate from user programs.

At some point there should be a folder just for the BIOS, which should
read from the boot block of the SD card and start executing, and thats
it.

sw/kernel/exec.h

@@ -0,0 +1,6 @@
+#ifndef _EXEC_H
+#define _EXEC_H
+
+void exec(char* filename);
+
+#endif