merge multi threading to master branch

- updated zstd to latest devel release
- lz4, lz5 and zstd is included now
- all three support threading

C/zstdmt/README.md

@@ -0,0 +1,66 @@
+
+# Multithreading Library for [LZ4], [LZ5] and [ZStandard]
+
+
+### Compression
+```
+typedef struct {
+	void *buf;		/* ptr to data */
+	size_t size;		/* current filled in buf */
+	size_t allocated;	/* length of buf */
+} LZ4MT_Buffer;
+
+/**
+ * reading and writing functions
+ * - you can use stdio functions or plain read/write ...
+ * - a sample is given in 7-Zip ZS or lz4mt.c
+ */
+typedef int (fn_read) (void *args, LZ4MT_Buffer * in);
+typedef int (fn_write) (void *args, LZ4MT_Buffer * out);
+
+typedef struct {
+	fn_read *fn_read;
+	void *arg_read;
+	fn_write *fn_write;
+	void *arg_write;
+} LZ4MT_RdWr_t;
+
+typedef struct LZ4MT_CCtx_s LZ4MT_CCtx;
+
+/* 1) allocate new cctx */
+LZ4MT_CCtx *LZ4MT_createCCtx(int threads, int level, int inputsize);
+
+/* 2) threaded compression */
+size_t LZ4MT_CompressCCtx(LZ4MT_CCtx * ctx, LZ4MT_RdWr_t * rdwr);
+
+/* 3) get some statistic */
+size_t LZ4MT_GetFramesCCtx(LZ4MT_CCtx * ctx);
+size_t LZ4MT_GetInsizeCCtx(LZ4MT_CCtx * ctx);
+size_t LZ4MT_GetOutsizeCCtx(LZ4MT_CCtx * ctx);
+
+/* 4) free cctx */
+void LZ4MT_freeCCtx(LZ4MT_CCtx * ctx);
+```
+
+### Decompression
+```
+typedef struct LZ4MT_DCtx_s LZ4MT_DCtx;
+
+/* 1) allocate new cctx */
+LZ4MT_DCtx *LZ4MT_createDCtx(int threads, int inputsize);
+
+/* 2) threaded compression */
+size_t LZ4MT_DecompressDCtx(LZ4MT_DCtx * ctx, LZ4MT_RdWr_t * rdwr);
+
+/* 3) get some statistic */
+size_t LZ4MT_GetFramesDCtx(LZ4MT_DCtx * ctx);
+size_t LZ4MT_GetInsizeDCtx(LZ4MT_DCtx * ctx);
+size_t LZ4MT_GetOutsizeDCtx(LZ4MT_DCtx * ctx);
+
+/* 4) free cctx */
+void LZ4MT_freeDCtx(LZ4MT_DCtx * ctx);
+```
+
+## Todo
+
+- add Makefile