Channeling units are now restricted by marked plot channeling restrictions.
Modifications to Builds capabilities.

Builds can now be made valid by the builder being in its owner's
territory.

Builds can now cause happiness while they are in progress.

Builds can now have exclusion zones around themselves where other builds
of certain types cannot be in progress at the same time.

The builds that are just 'change to this state' (eg. gleeman shows) do not
yet function. The button pops up and is active, but pressing it does
nothing. Investigation into CvUnitMission is required.