issues with non-ascii letters

When alink_text starts or ends with a non-ascii letter (for instance, accentuated letters), alink does recognized the text to be linked and ends up by ding nothing. Here is a proposed patch to fix this. This very useful and simple module does not seem to be maintained anymore, but I guess this patch could help people using it (like #339166: Module does not cover umlaut or #1472248: non-english characters aren't replaced) ...