showinfo: replace "CRC" by "checksum"
Indeed the Adler-32 checksum, which is computed by showinfo, is notcyclic, so using the term "CRC" is wrong/confusing.
showinfo: fix vertical align nit
showinfo: fix computation of Adler checksum
Previously the code was computing the checksum only for the first lineof each plane.
lavfi: rename AVFilterBufferRefVideoProps.pixel_aspect to sample_aspect_ratio
Improve consistency with libavcodec.
This breaks libavfilter API/ABI.
The non-sequential 2.1.0 -> 2.4.0 bump is due to the mess previouslydone with the lavfi minor number.
lavfi: add showinfo filter