Added Java demo to search for rise/set/culmination
of the Sun and Moon.
Also added the missing entry for the Kotlin
rise/set/culmination demo that I had forgotten.
Added Kotlin and Java demos for calculating Jupiter's moons.
Illustrates correcting for light travel time.
I added named getters for the 4 moons in `JupiterMoonsInfo`,
because in Java it was really ugly to write
`jm.getMoon()[0]`, etc.
This is the first substantial demo of using
the Kotlin version of Astronomy Engine from
a Java program.
Structured the README.md so I can keep adding more and
more demos as separate Java class files.
The `demotest` script builds the code and will run
each demo one at a time, verifying each one's output.
