Some core files converted to UTF-8; installers now compile and run under UNIX and WINE; ExUI can now be used in a detached NSIS root

!ifndef XPUI_SYSDIR
  !define XPUI_SYSDIR "${NSISDIR}\Contrib\ExperienceUI"
!endif
!include "${XPUI_SYSDIR}\XPUI.nsh"