API changes, most recent first:
+2017-04-11 - xxxxxxx - lavu 55.61.100 - avstring.h
+ Add av_strireplace().
+
+2016-04-06 - xxxxxxx - lavc 57.92.100 - avcodec.h
+ Add AV_PKT_DATA_CONTENT_LIGHT_LEVEL packet side data.
+
+2016-04-06 - xxxxxxx - lavu 55.60.100 - mastering_display_metadata.h
+ Add AV_FRAME_DATA_CONTENT_LIGHT_LEVEL value, av_content_light_metadata_alloc()
+ and av_content_light_metadata_create_side_data() API, and AVContentLightMetadata
+ type to export content light level video properties.
+
2017-03-31 - xxxxxxx - lavu 55.57.100 - spherical.h
Add av_spherical_projection_name().
Add av_spherical_from_name().