Add VS2012 update 4 version number.
Use pragma once.
Clean up structs/enums.
Update Changelog.txt.
Updated French translation.
Fix skipping to next/previous file in the folder when the current file isn't detected as a media file.

Also use a more adapted structure to hold the file list.
Update LAV Filters to 0.59.1-31-c635d2d (custom build based on 0.59.1-26-73db2ec).

Important changes:
 - Fix a freeze when changing the bitstreaming settings when paused (ticket #3688).
 - Avoid a possible crash with DXVA2 decoding.
AboutDlg: use same char count for the underline
Fix compilation of lite builds.

Use a more flexible way to define if internal filters should be enabled or disabled by default.