Update the context state properties separately

Update the context state properties separately

The context state properties are less likely to change compared to the listener
state, and future changes may prefer more infrequent updates to the context
state.

Note that this puts the MetersPerUnit in as a context state, even though it's
handled through the listener functions. Considering the infrequency that it's
updated at (generally set just once for the context's lifetime), it makes more
sense to put it there than with the more frequently updated listener
properties. The aforementioned future changes would also prefer MetersPerUnit
to not be updated unnecessarily.