remove outdated appveyor file

.appveyor_old.yml

@@ -1,57 +0,0 @@
-# Use the Appveyor build number for naming the build.
-# src: https://www.appveyor.com/docs/build-configuration/#build-versioning
-version: '{Windows}'
-# see https://www.appveyor.com/docs/how-to/repository-shallow-clone/
-shallow_clone: true
-
-platform: x64
-
-environment:
-  matrix:
-# CMake
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-    VS: 2017
-    CONFIG: Release
-    TEST: OFF
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-    VS: 2017
-    CONFIG: Release
-    TEST: ON
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-    VS: 2017
-    CONFIG: Debug
-    TEST: ON
-
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-    VS: 2015
-    CONFIG: Release
-    TEST: OFF
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-    VS: 2015
-    CONFIG: Release
-    TEST: ON
-  - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-    VS: 2015
-    CONFIG: Debug
-    TEST: ON
-
-matrix:
-  fast_finish: false
-
-before_build:
-  # see https://www.appveyor.com/docs/lang/cpp/#visual-studio-2017 
-  - if "%VS%"=="2017" call "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvars64.bat"
-  - if "%VS%"=="2017" set CMAKE_GENERATOR="Visual Studio 15 2017 Win64"
-  # see https://www.appveyor.com/docs/lang/cpp/#visual-studio-2015
-  - if "%VS%"=="2015" call "C:\Program Files\Microsoft SDKs\Windows\v7.1\Bin\SetEnv.cmd" /x64
-  - if "%VS%"=="2015" call "C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\vcvarsall.bat" x86_amd64
-  - if "%VS%"=="2015" set CMAKE_GENERATOR="Visual Studio 14 2015 Win64"
-
-build_script:
-  - cmake --version
-  - cmake -H. -Bbuild -DPHMAP_BUILD_TESTS=%TEST% -DPHMAP_BUILD_EXAMPLES=%TEST% -G %CMAKE_GENERATOR%
-  - cmake --build build --config %CONFIG% --target ALL_BUILD -- /maxcpucount
-
-test_script:
-  - if "%TEST%"=="ON" set CTEST_OUTPUT_ON_FAILURE=1
-  - if "%TEST%"=="ON" cmake --build build --config %CONFIG% --target RUN_TESTS