Fill-type functions used to return 0 for success, and -1
on failure. They now return the number of cells written
on success, similarly to ncvisual_render(). Resolves#427.
Certain unit tests required UTF8 encoding on the output
terminal to work (#428). This includes anything which does
any kind of fill. Add enforce_utf8() checks to all such
tests that were missing them. Unit tests once again pass in
a pure ASCII environment.
Introduce limited plane rotation capability. We currently support clockwise and counterclockwise rotation of planes. Square and rectangular geometries are both supported, but there must be an even number of columns. The atomic unit of rotation is a 2x1 "square" (this assumes .5 cell aspect ratio). We can only rotate those glyphs which have rotated equivalents, and not even all of those. We currently handle only:
* null glyph
* space
* upper half block
* lower half block
* full block
I've added unit tests as well. This functionality is used by our Tetris example in the book
