Introduce fs_configpath

Split fs_savepath for config files. This is in preparation for
moving the writable paths on *nix to $XDG_DATA_HOME and
$XDG_CONFIG_HOME.
Affected files: config.spec, *.cfg, doomkey, xpkey.

sys/sys_public.h

@@ -119,6 +119,7 @@ struct sysMemoryStats_t {
 
 enum sysPath_t {
 	PATH_BASE,
+	PATH_CONFIG,
 	PATH_SAVE,
 	PATH_EXE
 };