as multiboot kernels.

* Renamed caca_refresh() into caca_display() which makes more sense.
  * Optimised gl_bgpal by directly storing floats instead of doing the
    conversion at runtime.
  * Handle resizing in cucul_set_size() and try to keep as much information
    as possible from the previous canvas.
  * Moved most global variables into cucul_t or caca_t contexts.
  * Moved time.c into libcaca.

+ Check for sys/times.h and unistd.h.
    + Added calls to AC_C_CONST and AC_C_INLINE.
  * src/time.c src/graphics.c:
    + Fixes for MSVC compilation warnings.
    + Additional sanity checks in the Win32 driver.
  * src/caca.c:
    + Use raw()/noraw() in the curses driver instead of cbreak().
  * msvc/libcaca.sln:
    + Added an MSVC solution.
  * examples/aafire.c:
    + Slightly reduced the maximum cacafire framerate.

+ Better win32 check for Sleep().

+ Look for Sleep in -lkernel32.
  * examples/cacaview.c:
    + Use caca_wait_event() instead of usleep()/caca_get_event().

+ Native win32 port.

+ Check for gettimeofday().
  * src/time.c:
    + Created _caca_time().
    + Ported _caca_getticks() to the Win32 API.
  * src/caca.c:
    + Properly builds on Win32.
  * test/event.c:
    + Added <stdlib.h> because we use malloc().

+ Do not refresh after each event, but only when there is no event
      pending.
    + If the pressed key is a printable character, display it.
  * src/time.c:
    + Moved _caca_getticks() to this file.
  * src/caca.c:
    + Set the escape delay to a very low value in the ncurses driver,
      because I don't want escape sequences to be entered manually.
  * src/io.c:
    + Autorepeat emulation in the ncurses and slang drivers: do not
      immediately send the key release event.
  * configure.ac:
    + Check for usleep.
    + Improvements in the win32 platform detection.