Support for the Multiview extension of H.265/HEVC

[matteovn]

• A fix for the parsing of the SPS is provided. This is because for NALUs associated with layers whose identifier is greater than 0 the spec requires the decoder to parse sps_ext_or_max_sub_layers_minus1 (see F.7.3.2.2.1). The value of this syntax element is then used to infer the value for sps_max_sub_layers_minus1 as specified in Clause F.7.4.3.2.1. The current design would led to have sps_max_sub_layers_minus1 equal to zero. This is fine for streams captured by devices such as Apple iPhones since the value for sps_ext_or_max_sub_layers_minus1 is set to 7 and the spec in this case mandates that sps_max_sub_layers_minus1 assumes the same value transmitted in the SPS. However, different encoders might be setting sps_ext_or_max_sub_layers_minus1 to a different value, thus also sps_max_sub_layers_minus1 will be different from the value parsed in the VPS. The fix proposed in av_parser.c::gf_hevc_read_sps_bs_internal addresses some discrepancy between the implementation and the spec.
• Support is added to parse and embed in a .mov file the three dimension reference displays info SEI message from Clause G.14.2.3.3. Such a supplemental information is required to play Multiview content on devices such as the Apple Vision Pro. Having MP4box embedding such information would allow users to wrap Annex B HEVC streams into .mov containers.