message: appveyor: move to VS2017
diff: version: "{build}"
  # Operating system (build VM template)
  -os: Visual Studio 2015
  +os: Visual Studio 2017
  # build platform, i.e. Win32 (instead of x86), x64, Any CPU. This setting is optional.
  platform:
  @@ -28,31 +28,33 @@ init:
  # clone directory
  clone_folder: C:\dronecore
  +
  # scripts to run before build
  before_build:
  +
  - cd C:\dronecore
  - git submodule update --init --recursive --depth 20
  - cd C:\
  - - appveyor DownloadFile https://curl.haxx.se/download/curl-7.55.1.zip
  - - 7z x -y curl-7.55.1.zip
  + - appveyor DownloadFile https://curl.haxx.se/download/curl-7.56.1.zip
  + - 7z x -y curl-7.56.1.zip
  build: on
  build_script:
  - - call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" amd64
  - - cd curl-7.55.1\winbuild
  + - call "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvars64.bat"
  + - cd curl-7.56.1\winbuild
  - if "%configuration%"=="Debug" (
  - nmake /f Makefile.vc mode=static VC=14 MACHINE=x64 DEBUG=yes
  + nmake /f Makefile.vc mode=static VC=15 MACHINE=x64 DEBUG=yes
  ) else (
  - nmake /f Makefile.vc mode=static VC=14 MACHINE=x64 DEBUG=no
  + nmake /f Makefile.vc mode=static VC=15 MACHINE=x64 DEBUG=no
  )
  - cd C:\dronecore
  - md build
  - cd build
  - if "%configuration%"=="Debug" (
  - cmake -DWIN_CURL_INCLUDE_DIR:STRING="C:\curl-7.55.1\include" -DWIN_CURL_LIB:STRING="C:\curl-7.55.1\builds\libcurl-vc14-x64-debug-static-ipv6-sspi-winssl\lib\libcurl_a_debug.lib" -G "Visual Studio 14 2015 Win64" ..
  + cmake -DWIN_CURL_INCLUDE_DIR:STRING="C:\curl-7.56.1\include" -DWIN_CURL_LIB:STRING="C:\curl-7.56.1\builds\libcurl-vc15-x64-debug-static-ipv6-sspi-winssl\lib\libcurl_a_debug.lib" -G "Visual Studio 15 2017 Win64" ..
  ) else (
  - cmake -DWIN_CURL_INCLUDE_DIR:STRING="C:\curl-7.55.1\include" -DWIN_CURL_LIB:STRING="C:\curl-7.55.1\builds\libcurl-vc14-x64-release-static-ipv6-sspi-winssl\lib\libcurl_a.lib" -G "Visual Studio 14 2015 Win64" ..
  + cmake -DWIN_CURL_INCLUDE_DIR:STRING="C:\curl-7.56.1\include" -DWIN_CURL_LIB:STRING="C:\curl-7.56.1\builds\libcurl-vc15-x64-release-static-ipv6-sspi-winssl\lib\libcurl_a.lib" -G "Visual Studio 15 2017 Win64" ..
  )
  - if "%configuration%"=="Debug" (
  cmake --build . --target install --config Debug
  