t:htmlEntityDecode doesn't support all text entities.

[csanders-git]

Randomly this doesn't support all entities. like etc
See https://dev.w3.org/html5/html-author/charref for a list of others.

This is even brought up in the code:
https://github.com/SpiderLabs/ModSecurity/blob/caadf97524a4861456be176a8cb91dcbb76b97e4/apache2/msc_util.c#L1844