Emlog vulnerable to Deserialization of Untrusted Data

Emlog is an open source website building system. Versions 2.5.13 and prior have a deserialization vulnerability. A user who creates a carefully crafted nickname can cause `str_replace` to replace the value of `name_orig` with empty, causing deserialization to fail and return `false`. Commit 9643250802188b791419e3c2188577073256a8a2 fixes the issue.