Add a drupal_alter to alter original path before transliteration is called

Hi all,

I needed to alter original path before transliteration is called ( because it replaced a special char by another one, so pathauto could not make difference between them, and I needed "'" to be replaced by nothing, and "’" to be replaced by a dash ( the difference is very hard to see ;-) ).

I added a drupal_alter on pathauto module to replace directly my "’" with a '-' so my aliases are now generated properly! ( at least, how I want them to be ).

I'll upload my patch soon.