to the flip/flop/rotation filters.

* Updated text test.

as bold or underline. No higher level support for these yet, but at
    least everything is consistent.
  * Created cucul_set_attr_ansi() and cucul_set_attr_argb() which are bound
    to replace cucul_set_color() and cucul_set_truecolor().

documentation errors or imprecisions.

fullwidth characters.
  * Added a case to test/fullwidth.c for cucul_blit and fullwidth chars.

* Made these functions fullwidth-aware.

in all .c files that needed it.

* Renamed canvas handle variables from "c" to "cv". Eh ouais mon gros.

remove redundencies in the Doxygen documentation.

operations on canvases.