avframe: add AVFieldState enum and add it to AVFrame
ffv1dec: use AVFieldState instead of interlaced_frame and top_field_first
ffv1enc: use AVFieldState instead of interlaced_frame and top_field_first
proresdec: use AVFieldState instead of interlaced_frame and top_field_first
proresenc: use AVFieldState instead of top_field_first
dnxhddec: use AVFieldState instead of interlaced_frame and top_field_first
dnxhdenc: use AVFieldState instead of interlaced_frame and top_field_first
pngdec: use AVFieldState instead of interlaced_frame

This commit also correctly marks the interlace type of adam7
which does not correspond to bff or tff interlacing.
dvdec: use AVFieldState instead of interlaced_frame and top_field_first
frwu: use AVFieldState instead of interlaced_frame and top_field_first
utvideodec: use AVFieldState instead of interlaced_frame

This commit also correctly marks the orthogonal interlace mode of utvideo
which does not correspond to bff or tff interlacing.
libx264: use AVFieldState instead of top_field_first
mjpegdec: use AVFieldState instead of interlaced_frame and top_field_first
mpeg12enc: use AVFieldState instead of top_field_first
mpeg4videoenc: use AVFieldState instead of top_field_first
avconv: use AVFieldState instead of interlaced_frame and top_field_first
yuv4mpeg: use AVFieldState instead of interlaced_frame and top_field_first
v4l2: use AVFieldState instead of interlaced_frame and top_field_first
avframe: use AVFieldState instead of interlaced_frame and top_field_first
vsrc_testsrc: use AVFieldState instead of interlaced_frame