Put LAVFilters files in a different folder when using x64.
Update installer.

Delete old LAVFilters for the x64 build.
Update VirtualDub to v1.10.4-test11.
Run astyle.
Shave off a few more bytes from png files.
src\thirdparty\LAVFilters\build_lavfilters.bat: Keep the style consistent.
installer: reindent and remove commented code.
Initialize variables.
Add Windows 8.1 ID in the manifest files.