pyterm: adds timer function

/timer <interval> <command> now allows to schedule arbitrary commands to
be send to the node after the specified interval (in seconds).
I don't understand the code.

```
In [1]: line = "foobar foo bar"

In [2]: x,y = line.split()
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-2-ce25c40bcd75> in <module>()
----> 1 x,y = line.split()

ValueError: too many values to unpack (expected 2)
```