This is what the XDG Base Directory Specification suggests to use. We still
use ~/.scummvm as default path in case the directory exists.
This tackles an aspect of bug #6036 "POSIX: Use XDG dirs instead of HOME".
Right now, a few places in the frontend code still use printf and
consorts. We mark the affected files with a FIXME for now, and
add a dedicated exception for each. To be fixed!
Also tweak FORBIDDEN_SYMBOL_REPLACEMENT to hopefully really always
enforce a compiler error
* add a subclass of DefaultSaveFileManager for UNIX, POSIXSaveFileManager, which overloads checkPath
* switched SDL backend to use POSIXSaveFileManager if UNIX is #defined
svn-id: r34872