Add support for horizontal scanning strategies that cross the north-s…

[keskitalo]

…outh meridian

[keskitalo]

Example hit map for a Chilean telescope with a 10-degree FOV, observing three Southern horizontal patches at 50, 55 and 60 degrees, each with 60-degree azimuth throw. The period is January and Sun is avoided at 30-degree boresight distance.

[keskitalo]

Another example that uses 45-degree avoidance around the Moon and the Sun. Northern targets were provided for times when the South direction is blocked. FOV is 30 degrees.