perf: new row64 mode, used notably in levels 11 & 12, by @senhuang42
perf: minor compression ratio improvements for small data at high levels, by @cyan4973
perf: reduced stack usage (mostly useful for Linux Kernel), by @terrelln
-perf: faster detection and skipping of incompressible blocks, by @bindhvo
+perf: faster compression speed on incompressible data, by @bindhvo
perf: on-demand reduced ZSTD_DCtx state size, using build macro ZSTD_DECODER_INTERNAL_BUFFER, at a small cost of performance, by @bindhvo
build: allows hiding static symbols in the dynamic library, using build macro, by @skitt
build: support for m68k (Motorola 68000's), by @cyan4973