Merge pull request #1253 from rouault/floating_point_irreversible_encoding

Single-threaded performance improvements in forward DWT for 5-3 and 9-7 (and other improvements)

diff --cc src/lib/openjp2/j2k.c
Simple merge

diff --cc src/lib/openjp2/t1.c
Simple merge

diff --cc tests/nonregression/CMakeLists.txt
Simple merge