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/7zAlloc.c

@@ -0,0 +1,80 @@
+/* 7zAlloc.c -- Allocation functions
+2017-04-03 : Igor Pavlov : Public domain */
+
+#include "Precomp.h"
+
+#include <stdlib.h>
+
+#include "7zAlloc.h"
+
+/* #define _SZ_ALLOC_DEBUG */
+/* use _SZ_ALLOC_DEBUG to debug alloc/free operations */
+
+#ifdef _SZ_ALLOC_DEBUG
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+#include <stdio.h>
+int g_allocCount = 0;
+int g_allocCountTemp = 0;
+
+#endif
+
+void *SzAlloc(ISzAllocPtr p, size_t size)
+{
+  UNUSED_VAR(p);
+  if (size == 0)
+    return 0;
+  #ifdef _SZ_ALLOC_DEBUG
+  fprintf(stderr, "\nAlloc %10u bytes; count = %10d", (unsigned)size, g_allocCount);
+  g_allocCount++;
+  #endif
+  return malloc(size);
+}
+
+void SzFree(ISzAllocPtr p, void *address)
+{
+  UNUSED_VAR(p);
+  #ifdef _SZ_ALLOC_DEBUG
+  if (address != 0)
+  {
+    g_allocCount--;
+    fprintf(stderr, "\nFree; count = %10d", g_allocCount);
+  }
+  #endif
+  free(address);
+}
+
+void *SzAllocTemp(ISzAllocPtr p, size_t size)
+{
+  UNUSED_VAR(p);
+  if (size == 0)
+    return 0;
+  #ifdef _SZ_ALLOC_DEBUG
+  fprintf(stderr, "\nAlloc_temp %10u bytes;  count = %10d", (unsigned)size, g_allocCountTemp);
+  g_allocCountTemp++;
+  #ifdef _WIN32
+  return HeapAlloc(GetProcessHeap(), 0, size);
+  #endif
+  #endif
+  return malloc(size);
+}
+
+void SzFreeTemp(ISzAllocPtr p, void *address)
+{
+  UNUSED_VAR(p);
+  #ifdef _SZ_ALLOC_DEBUG
+  if (address != 0)
+  {
+    g_allocCountTemp--;
+    fprintf(stderr, "\nFree_temp; count = %10d", g_allocCountTemp);
+  }
+  #ifdef _WIN32
+  HeapFree(GetProcessHeap(), 0, address);
+  return;
+  #endif
+  #endif
+  free(address);
+}