I've just added some DirectShow headers:
I've added them to the 'include' directory since DirectShow is
documented as being part of the Microsoft SDK.
For example AMGetErrorText() is now declared in include/errors.h:
On the other hand it was already defined in lib/directx/quartz.def, not
This is not consistent. Either lib/directx/quartz.def should be moved to
lib/quartz.def, or include/errors.h should be moved to
include/directx/errors.h. Which is best?