Windows: Protect against using a container file as its own keyfile. Normalizing path names to never use '/' but always '\'.

src/Common/Language.xml

@@ -647,6 +647,7 @@
     <string lang="en" key="SELECT_KEYFILE">Select Keyfile</string>
     <string lang="en" key="SELECT_KEYFILE_PATH">Select a keyfile search path. WARNING: Note that only the path will be remembered, not the filenames!</string>
     <string lang="en" key="SELECT_KEYFILE_GENERATION_DIRECTORY">Select a directory where to store the keyfiles.</string>
+    <string lang="en" key="SELECTED_KEYFILE_IS_CONTAINER_FILE">The current container file was selected as a keyfile. It will be skipped.</string>
     <string lang="en" key="SERPENT_HELP">Designed by Ross Anderson, Eli Biham, and Lars Knudsen. Published in 1998. 256-bit key, 128-bit block. Mode of operation is XTS. Serpent was one of the AES finalists.</string>
     <string lang="en" key="SIZE_HELP">Please specify the size of the container you want to create.\n\nIf you create a dynamic (sparse-file) container, this parameter will specify its maximum possible size.\n\nNote that the minimum possible size of a FAT volume is 292 KB. The minimum possible size of an NTFS volume is 3792 KB.</string>
     <string lang="en" key="SIZE_HELP_HIDDEN_HOST_VOL">Please specify the size of the outer volume to be created (you will first create the outer volume and then a hidden volume within it). The minimum possible size of a volume within which a hidden volume is intended to be created is 340 KB.</string>