If you use pano mode, the system renders your scene by "turning" the camera so it collects XPARTS consecutive images edge to edge. For example, 640x480 with XPARTS=3 will give a 1920x480 image which changes perspective from left, center and right view directions.

If you make a sufficiently narrow render resolution such as 4x480, you can emulate a "slit-scan" panoramic camera, giving a seamless cylindrical projection.

But there was an artificial limit of 64 XPARTS and also XPARTS*YPARTS<64. I found no reason for this limit in the current codebase, so this patch removes it. This lets you render full 360-degree (and wider) cylindrical panoramas with up to 1000 xparts.

(A sample test render is at http://halley.cc/nihon/yanagi-dojo-12-outside-pano.jpg for your enjoyment. May disappear in a week or so.)

I also allow yparts to go up to 1000, but there's still a check that panoramas are only single row horizontal. I'll check if that's required later. Removing that constraint could allow 360x180 degree spherical projection output.