This uses the new implicit conversions and constructors
that have been committed in the previous commit.
I tested these changes on Linux with gcc and on Windows.
This was the last of the three network optimizations I developed in
the functions branch. Common subnetwork elimination and constant
folding together can get rid of most unnecessary nodes.
Those optimizations work on the multi-function network level.
Not only will they make the network evaluation faster, but they also
simplify the network a lot. That makes it easier to understand the
exported dot graph.
