improving getSunTransit() depending on AstronomicalCalculator

[msalle]

The current ZmanimCalendar#getChatzos() uses the midpoint between sunrise and sunset (see AstronomicalCalendar.java#getSunTransit()). As you say, this is following most opinions. On the other hand, I have found some poskim actually using the real transit time for their calculation and it would be very useful to have access to it. Using the NOAACalculator#getSolarNoonUTC() an actual transit calculation is available, but given that it is a private method, it cannot be accessed externally. I would suggest to:

1. change ZmanimCalendar#getChatzos() to there calculate use the sunrise and sunset instead of calling getSunTransit()
2. to create a getSunTransit() in each AstronomicalCalculator implementation
3. to redefine the AstronomicalCalendar.java#getSunTransit() to calculate using a call to the getSunTransit() in the underlying AstronomicalCalculator.
4. or as alternative to 2. and 3. provide a default in AstronomicalCalculator itself which can then be overridden in e.g. NOAACalculator