Update for FFmpeg 3.2.18

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

Changelog

 Entries are sorted chronologically from oldest to youngest within each release,
 releases are sorted from youngest to oldest.
 
+version 3.2.18:
+ avfilter/vf_colorspace: fix memmory leaks
+ avcodec/ac3enc: Fix memleak
+ avformat/nutenc: don't allocate a dynamic AVIOContext if no index is going to be written
+ avfilter/vf_random: fix memory leaks
+ avfilter/vf_bwdif: fix heap-buffer overflow
+ fftools/ffmpeg_opt: Fix leak of options when parsing options fails
+ avfilter/vf_edgedetect: fix heap-buffer overflow
+ avfilter/vf_w3fdif: deny processing small videos
+ avfilter/vf_avgblur: fix heap-buffer overflow
+ avfilter/af_tremolo: fix heap-buffer overflow
+ avfilter/vf_edgedetect: check if height is big enough
+ avfilter/vf_bitplanenoise: fix overreads
+ avfilter/vf_fieldorder: fix heap-buffer overflow
+ avfilter/vf_fieldmatch: fix heap-buffer overflow
+ aformat/movenc: add missing padding to output track extradata
+ avcodec/pngenc: remove monowhite from apng formats
 
 version 3.2.17:
  configure: bump year

RELEASE

-3.2.17
+3.2.18

doc/Doxyfile

@@ -38,7 +38,7 @@ PROJECT_NAME           = FFmpeg
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 3.2.17
+PROJECT_NUMBER         = 3.2.18
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a