v2 bugfixes

v2 fixes:

• compatibility with api4 video plugins that invoke v4 std filter core.std.ShufflePlanes (the colorfamily parameter needs to be translated.)
• set VSCoreInfo::numThreads.

initial release

Suppose you are stuck with VS R54, but you want to use a video plugin filter.dll
that only has api4 support. You can download the released api3.dll and save it
as filter.api3.dll along side with filter.dll into VS plugins directory. And then
you should be able to use the filter in api3 VS as usual.