changed name frameParams into frameHeader

ZSTD_frameParams => ZSTD_frameHeader
ZSTD_getFrameParams() -> ZSTD_getFrameHeader()

The new naming is more distinctive from ZSTD_frameParameters,
which is used during compression.

ZSTD_frameHeader is clearer in its intention to described frame header content.
It also implies we are decoding a ZSTD frame, hence we are at decoding stage.

lib/zstd.h

@@ -746,10 +746,10 @@ typedef struct {
     unsigned windowSize;
     unsigned dictID;
     unsigned checksumFlag;
-} ZSTD_frameParams;
+} ZSTD_frameHeader;
 
 /*=====   Buffer-less streaming decompression functions  =====*/
-ZSTDLIB_API size_t ZSTD_getFrameParams(ZSTD_frameParams* fparamsPtr, const void* src, size_t srcSize);   /**< doesn't consume input, see details below */
+ZSTDLIB_API size_t ZSTD_getFrameHeader(ZSTD_frameHeader* fparamsPtr, const void* src, size_t srcSize);   /**< doesn't consume input, see details below */
 ZSTDLIB_API size_t ZSTD_decompressBegin(ZSTD_DCtx* dctx);
 ZSTDLIB_API size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t dictSize);
 ZSTDLIB_API void   ZSTD_copyDCtx(ZSTD_DCtx* dctx, const ZSTD_DCtx* preparedDCtx);