Data structure representing virtual z-layers

[dankamongmen]

If we want to do libpanelw-like stuff, the first thing we'll need is a good data structure for maintaining multiple virtual screens along a z axis. Each cell must be able to hold its own wchar_t and attributes, including color of some depth.

[dankamongmen]

I've introduced the cell structure and alloc_plane() to set them up...

[dankamongmen]

I've introduced the ncplane structure, which comprises:

• lenx and leny, dimensions of the plane
• x and y, current position in the plane, 0 <= x < lenx etc.
• absx and absy, position of the origin relative to the true terminal
• a flat array of cells equal to lenx * leny for the plane
• z, a pointer to the next plane in the z-buffer

[dankamongmen]

We're now properly rendering with ncplanes all over the place :D.