These files can replace their equivalent in fesapi in order to get Unicode support for Fesapi CSharp. You must reconfigure/regenerate your build with cmake after replacement.
Fesapi is released under Apache 2.0 license. These files are released under The Code Project Open License (CPOL): http://www.codeproject.com/info/cpol10.aspx.
Because CPOL license is not compatible with Apache 2.0 license, these files are delivered in a separate repository than fesapi.