Avoid empty files if the encoding isnt ascii

[landryb]

If the awstats data file is iso-8859, htmlspecialchars barfs and returns an empty string, and thus clsAwstats cant parse the file, and returns 0 visits/pages/etc. Adding ENT_SUBSTITUTE worksaround this..

[bacinsky]

Commit 91053db cherry-picked into develop branch but the 1648554 results in conflict cause there is a workaround using ENT_IGNORE already, use develop branch not master, for latest code.