* Use RETVAL_STRINGL instead of RETURN_STRINGL in function caca_export_string

this is [0, 127], rather than [0, 255]; always free the temporary
pixels copy allocated in PHP_FUNCTION(caca_dither_bitmap); fix a typo
which caused PHP_FUNCTION(caca_set_display_title) to crash due to a
failed run-time binding to "caca_set_display" (the "_title" was
missing).

caca_export_string

* Destroy php resource in caca_file_close
* Improve sample program render.php

* Add php bindings for caca_get_dither_antialias_list, caca_render_canvas
* Add a new sample program examples/render.php

* caca_dithering_bitmap can load palette from gd resource
* Remove caca_set_dither_palette_gd function
* Adapt sample program "dithering.php"

* caca_get_event return false if type == CACA_EVENT_NONE otherwise return a new
  php resource
* Adapt sample program demo.php

* Change php header for sample program "text.php"

* Adapt sample programs

* Add a sample program examples/polyline.php

* Add a working sample file examples/figfont.php
* Rename sample programs:
     examples1.php > cacapig.php
     drivers.php > cacainfo.php

* Add php binding for caca_file_gets

* Modify php bloc headers in samples programs
* Add list of import/export formats in examples/drivers.php

given gd resource.

render it with caca caca_dither_bitmap_gd)
* Add a function to fetch a buffer of gd pixels in php_caca.c

* Add php binding for "caca_create_dither"
* Add new sample program "dithering.php"

resources such as gd resouces
* Add test for presence of gd development files in config.m4
* Rename php function caca_dither_bitmap in caca_dither_bitmap_gd

caca_get_dither_algorithm

* Add just_for_fun() function in sample program drivers.php

* Add new sample program "examples/drivers.php"

* Add binding for 2 new functions
* Fix a bug in examples/example1.php

* Add "full" demo to "examples/demo.php"

* Improve examples/demo.php

* Create a new sample file demo.php (php port of demo.c)

* Animate pink pig & add event managment in sample program "example1.php"

* Add a nice php sample file examples/example1.php that shows a smart pink ping

* Add php binding for 13 new functions