This removes ReadFile(), WriteFile(), ReadLine(), Lower() and Upper() from
Utils.h and adds CFile::ReadFile().
The biggest part of this patch fixes modules to use CFile and CString instead
of these global functions.
git-svn-id: https://znc.svn.sourceforge.net/svnroot/znc/trunk@1311 726aef4b-f618-498e-8847-2d620e286838