- some Kconfig simplifications
 - FIELD_ALTERNATE capture was broken, add a "wait for vbi" command
   before actually waiting for the field change
 - improvements regarding streaming capture to gfx card memory.
 - captured frames could only be page aligned.  fixed.
 - fix pgtable_build_single, it should work for all kinds of buffers now
   (system memory (kernel/user) and gfx-memory)
 - Fix bytesperline-calculation for V4L2_FIELD_ALTERNATE vs.
   V4L2_FIELD_INTERLACED capture