Corectly convert alpha recived from imageColorForIndex to 1byte 0-255, 0 being transparent.
Recivied is a number between 0 and 127 where
127 is transparent.
Replace freeing of Image resource in destructor with a destroy method
This is to prevent confusion in the case one might retrive the
raw image resource, and the image is freed.
$image = new Image(100, 100);
$res = $image->asImageResource();
unset($image);
//$res should still be a good resource
fix #17
Implement Image->getFontCollection()
Fix x-y and width-height confusion
Add Point test case
Write tests for Image class