remove redundencies in the Doxygen documentation.

secure against broken files, but it probably needs peer review.

* Fixed font selection through cucul_font_load().
  * Added a bigger 10x19 bold font.

* Removed ugly hooks from test/font.c.

* Documented most font functions.
  * Cleaned up cucul_render_canvas() and made it actually usable by external
    programs. Removed ugly printf() debug calls.

* Replaced the 8-bit internal font with a 4-bit one.

fg/bg value into its separate argb 4-bit fields.

for the moment.

skeleton for the renderer that will not last very long.

format proposal is in this file. Feel free to comment.

* Removed '\x0f' from the IRC exporter until I understand why it was here.

really portable, and Visual Studio complains when they are not explicitely
    cast.

* Fixed exporter headers to make Doxygen happy.

* Ooops. Compilation fix.   \,'    '-._.-\  '     ` .-'
                             .'            /         (
                            /    S        |     _   _ \
                           |        a     \     o   o  |
                           ;           m         .-.   /
                            ;       ',       '-.( '')-'
                             '.      |           ;-'
                               \    /           /
                               /   /-._  __,  7 |
                               \  `\  \``  |  | |
                                \   \_,\   |  |_,\
                                 '-`'      \_,\

environment variables handling. Replaced that with three per-bitmap
    functions: cucul_set_bitmap_antialias(), cucul_set_bitmap_color() and
    cucul_set_bitmap_dithering().
  * Added cucul_set_bitmap_brightness() and cucul_set_bitmap_contrast()
    prototypes (but did not implement them yet).
  * Added cucul_set_bitmap_charset() to choose what characters are going
    to be used for the bitmap rendering.
  * Removed the now useless cucul_get_feature(), cucul_set_feature() etc.

can add new exporters without changing the API.

raw driver. I know it is inconsistent to have the loader in libcucul
    and the exporter in libcaca but I'll find a way to harmonise that.

AHAHAH                      _
    _._ _..._ .-',     _.._(`))
   '-. `     '  /-._.-'    ',/
      ) MAIS    \            '.
     / _    _    |  JE         \
    |  a    a    /     SUIS     |
    \   .-.                     ;  
     '-('' ).-'       ,' UN    ;
        '-;           |      .'
           \    VIEUX  \    /
           | 7  .__  _.-\   \
           | |  |  ``/  /`  /
          /,_|  |   /,_/   /
             /,_/      '`-'

POOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOORC!

* Changed the line, box, ellipsis etc. prototypes so that they use an UTF-8
    string instead of a single character as their last argument.

operations on canvases.