dcf21
Generalising Alt-Az projection
Alt-Az projection now takes angular width in the interval (0°, 360°) as a parameter. Having a projection capable of drawing charts with angular width greater than 180° might be useful: an exaple is drawing a chart of all stars you can see fron your latitude. Ticks on the edge of the chart, as in the gnomonic projection, make it way easier to read, so I implemented them on the edge of Alt-Az charts too. In some cases, for example when the projection is centered on a pole, some parallels might never intersect the edge, so I added the possobility to draw the RA=0 meridian and label the intersections of constant Declinaton parallels with it. I called that meridian "Vernal Meridian" in the legend, I hope it's the correct name.
