add ota algorithm for device

1. effective "Differential Upgrade" patch algorithm with high compression rate
2. effective recovery algorithm support recovery firmware in blocks which has low memory consumption and wear-leveling strategies, especially suitable for embeded devices with low RAM.
3. add sample ota bootloader project, see:
board\TencentOS_tiny_EVB_MX_Plus\KEIL\ota\ota_bootloader_recovery
4. add sample application project for download firmware through http, see:
board\TencentOS_tiny_EVB_MX_Plus\KEIL\ota\ota_application_download_through_http
5. add sample application project for download firmware through qcloud explorer console, see:
board\TencentOS_tiny_EVB_MX_Plus\KEIL\ota\ota_application_download_through_qcloud_iot_explorer
6. an OTA markdown document is pending

components/ota/common/lzma/3rdparty/7zFile.h

@@ -0,0 +1,83 @@
+/* 7zFile.h -- File IO
+2017-04-03 : Igor Pavlov : Public domain */
+
+#ifndef __7Z_FILE_H
+#define __7Z_FILE_H
+
+#ifdef _WIN32
+#define USE_WINDOWS_FILE
+#endif
+
+#ifdef USE_WINDOWS_FILE
+#include <windows.h>
+#else
+#include <stdio.h>
+#endif
+
+#include "7zTypes.h"
+
+EXTERN_C_BEGIN
+
+/* ---------- File ---------- */
+
+typedef struct
+{
+  #ifdef USE_WINDOWS_FILE
+  HANDLE handle;
+  #else
+  FILE *file;
+  #endif
+} CSzFile;
+
+void File_Construct(CSzFile *p);
+#if !defined(UNDER_CE) || !defined(USE_WINDOWS_FILE)
+WRes InFile_Open(CSzFile *p, const char *name);
+WRes OutFile_Open(CSzFile *p, const char *name);
+#endif
+#ifdef USE_WINDOWS_FILE
+WRes InFile_OpenW(CSzFile *p, const WCHAR *name);
+WRes OutFile_OpenW(CSzFile *p, const WCHAR *name);
+#endif
+WRes File_Close(CSzFile *p);
+
+/* reads max(*size, remain file's size) bytes */
+WRes File_Read(CSzFile *p, void *data, size_t *size);
+
+/* writes *size bytes */
+WRes File_Write(CSzFile *p, const void *data, size_t *size);
+
+WRes File_Seek(CSzFile *p, Int64 *pos, ESzSeek origin);
+WRes File_GetLength(CSzFile *p, UInt64 *length);
+
+
+/* ---------- FileInStream ---------- */
+
+typedef struct
+{
+  ISeqInStream vt;
+  CSzFile file;
+} CFileSeqInStream;
+
+void FileSeqInStream_CreateVTable(CFileSeqInStream *p);
+
+
+typedef struct
+{
+  ISeekInStream vt;
+  CSzFile file;
+} CFileInStream;
+
+void FileInStream_CreateVTable(CFileInStream *p);
+
+
+typedef struct
+{
+  ISeqOutStream vt;
+  CSzFile file;
+} CFileOutStream;
+
+void FileOutStream_CreateVTable(CFileOutStream *p);
+
+EXTERN_C_END
+
+#endif