Started libsys and implemented public APIs for stack.

Signed-off-by: Christian Gunderman <christian@sonofboss.cwru.edu>
Implemented _sys_getchar() function.

Signed-off-by: Christian Gunderman <christian@sonofboss.cwru.edu>
Implemented _type() script function.

Signed-off-by: Christian Gunderman <christian@sonofboss.cwru.edu>
Implemented _file_delete() script function.