Info about new steps.
Implementing hotmodel.HotObject.

HotObject can hold properties that fire events when updated.
Properties can be other hot structures (HotObject, HotList, ...)
production.py better explains the meaning of the example.
Comments.
More readeable code.

In __setattr__ first getting rid of the special case - properties starting
with _
Unified the hot constants into the hot properties.

make_hot_constant not needed anymore, the constants now have to be
subclassed of HotBase, which makes them easy to detect in the hot
properties.
Merge branch 'master' of github.com:petrblahos/modellerkit