+ Add support for generation of PLT markers in encoder
+
+ * -PLT switch added to opj_compress
+ * Add a opj_encoder_set_extra_options() function that
+ accepts a PLT=YES option, and could be expanded later
+ for other uses.
+
+ -------
+
+ Testing with a Sentinel2 10m band, T36JTT_20160914T074612_B02.jp2,
+ coming from S2A_MSIL1C_20160914T074612_N0204_R135_T36JTT_20160914T081456.SAFE
+
+ Decompress it to TIFF:
+ ```
+ opj_uncompress -i T36JTT_20160914T074612_B02.jp2 -o T36JTT_20160914T074612_B02.tif
+ ```
+
+ Recompress it with similar parameters as original:
+ ```
+ opj_compress -n 5 -c [256,256],[256,256],[256,256],[256,256],[256,256] -t 1024,1024 -PLT -i T36JTT_20160914T074612_B02.tif -o T36JTT_20160914T074612_B02_PLT.jp2
+ ```
+
+ Dump codestream detail with GDAL dump_jp2.py utility (https://github.com/OSGeo/gdal/blob/master/gdal/swig/python/samples/dump_jp2.py)
+ ```
+ python dump_jp2.py T36JTT_20160914T074612_B02.jp2 > /tmp/dump_sentinel2_ori.txt
+ python dump_jp2.py T36JTT_20160914T074612_B02_PLT.jp2 > /tmp/dump_sentinel2_openjpeg_plt.txt
+ ```
+
+ The diff between both show very similar structure, and identical number of packets in PLT markers
+
+ Now testing with Kakadu (KDU803_Demo_Apps_for_Linux-x86-64_200210)
+
+ Full file decompression:
+ ```
+ kdu_expand -i T36JTT_20160914T074612_B02_PLT.jp2 -o tmp.tif
+
+ Consumed 121 tile-part(s) from a total of 121 tile(s).
+ Consumed 80,318,806 codestream bytes (excluding any file format) = 5.329697
+ bits/pel.
+ Processed using the multi-threaded environment, with
+ 8 parallel threads of execution
+ ```
+
+ Partial decompresson (presumably using PLT markers):
+ ```
+ kdu_expand -i T36JTT_20160914T074612_B02.jp2 -o tmp.pgm -region "{0.5,0.5},{0.01,0.01}"
+ kdu_expand -i T36JTT_20160914T074612_B02_PLT.jp2 -o tmp2.pgm -region "{0.5,0.5},{0.01,0.01}"
+ diff tmp.pgm tmp2.pgm && echo "same !"
+ ```
+
+ -------
+
+ Funded by ESA for S2-MPC project
+
+commit 64689d05dfaaf52105581d93fb1eb173b20829a4
+Author: Even Rouault <even.rouault@spatialys.com>
+Date: 2020-04-18 18:25:44 +0200
+
+ struct opj_j2k: remove unused fields, and add some documentation