ffplay: factorize frame queue operations

Create a generic frame and a frame queue struct to handle video picture queues
and subtitle picture queues with common code. Also add the possibility to queue
AVFrames, however at the moment we only use SDL_Overlay buffers for video and
AVSubtitles for subtitles.

Signed-off-by: Marton Balint <cus@passwd.hu>
ffplay: use frame queue to determine last used pos

Signed-off-by: Marton Balint <cus@passwd.hu>
Revert "avformat/rtpproto: fix strict aliasing violations with sockaddr"

It appears this breaks build with MSVC
until someone who has MSVC setup has time to investigate and
workaround/fix this, its better to revert so that build is not broken
Thats even more so as the original commit only fixed a hypothetical issue

This reverts commit e587a428d75d58e2e5a592efd7bff44e1d9294ee.
doc/filters: add geq gradient examples

Radial gradient by Víctor Paesa. Linear gradient by Paul Gentemann.

Also-by: Víctor Paesa <victorpaesa@googlemail.com>
Also-by: Paul Gentemann <beriukay@gmail.com>
Signed-off-by: Lou Logan <lou@lrcd.com>
avformat/avienc: Dont search for startcodes in inserted empty avi frames

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge remote-tracking branch 'cus/stable'

* cus/stable:
  ffplay: use frame queue to determine last used pos
  ffplay: factorize frame queue operations

Merged-by: Michael Niedermayer <michaelni@gmx.at>
ffplay: try to fix build failure on apple

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>