subset of the functionality of the .NET version; added Display::getEvent
similar to the .NET version; change Dither::bitmap to take a Canvas
object rather than a caca canvas resource as its first parameter; add
Font::Render and Font::getList methods parallel to the .NET version

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).

readability of fullwidth characters better by not placing cell
boundaries between them unneccessarily

(this actually happens with the cocoa driver!)

of the formats (so far, html, html3, bbfr, and svg)

sometimes send them to external viewers and become confused if the
filename ends in '.php' (despite our correct content-type!)

C predecessor.