Complete the Pendulum Example

Add initial equation, start value

Signed-off-by: Christoph Höger <choeger@umpa-net.de>
Add Pendulum Example

Signed-off-by: Christoph Höger <choeger@umpa-net.de>
Remove debug code

Signed-off-by: Christoph Höger <choeger@umpa-net.de>
Set start values

Signed-off-by: Christoph Höger <choeger@umpa-net.de>
Use new model constructor

Signed-off-by: Christoph Höger <choeger@umpa-net.de>
Add toString() methods
Make data available to outside

(Just for now, simpler observing)

Signed-off-by: Christoph Höger <choeger@umpa-net.de>