speedups when the calling application knows the dirty rectangle covered by
a complex operation.

a more natural (x,y,w,h) 4-tuple to handle.

inner implementation still only handles one dirty rectangle, but this way
we can prepare supporting applictions for the future.

that anything outside the dirty rectangle is guaranteed to be unchanged, but
we currently mark far too many cells as dirty. This must be optimised.

are almost there.

split is rendered moot by the plugin system: when enabled, binaries do
not link directly with libX11 or libGL. I hope this is a step towards
more consisteny and clarity.

far better for error checking.

<cucul.h> will provide the C99 types, even if libcaca has been installed.
  * Rename what's left of "common.h" to "stubs.h".
  * Remove all references to erroneous <inttypes.h> from source files.

due to spaces.

* Added a few additional character pairs of the left/right rotations.
  * Added missing errno sets.

cucul_stretch_* to avoid long function names. And the pairwise rotations
    look so nice now that they should be the real rotation chars.

* Updated test/text to show what the wide rotations now do.

suck massively for now.

* Renamed cucul_rotate into cucul_rotate_180.
  * Deprecated cucul_rotate and fix examples accordingly.
  Hope it all makes sense.

Sittler.

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.