Switch to the supported VS versions on Appveyor

appveyor.yml

@@ -8,12 +8,12 @@ branches:
 
 environment:
     matrix:
-        - msvc: 2013
         - msvc: 2015
+        - msvc: 2017
 
 platform:
-    - Win32
-#   - x64
+#   - Win32
+    - x64
 
 configuration:
     - Debug
@@ -27,16 +27,10 @@ os: Visual Studio 2015
 clone_depth: 1
 
 cache:
-    - C:\projects\openmw\deps\Bullet-2.83.7-msvc2013-win32.7z
-    - C:\projects\openmw\deps\Bullet-2.83.7-msvc2013-win64.7z
     - C:\projects\openmw\deps\Bullet-2.83.7-msvc2015-win32.7z
     - C:\projects\openmw\deps\Bullet-2.83.7-msvc2015-win64.7z
-    - C:\projects\openmw\deps\MyGUI-3.2.3-git-msvc2013-win32.7z
-    - C:\projects\openmw\deps\MyGUI-3.2.3-git-msvc2013-win32.7z
     - C:\projects\openmw\deps\MyGUI-3.2.3-git-msvc2015-win64.7z
     - C:\projects\openmw\deps\MyGUI-3.2.3-git-msvc2015-win64.7z
-    - C:\projects\openmw\deps\OSG-3.4.0-scrawl-msvc2013-win32.7z
-    - C:\projects\openmw\deps\OSG-3.4.0-scrawl-msvc2013-win32.7z
     - C:\projects\openmw\deps\OSG-3.4.0-scrawl-msvc2015-win64.7z
     - C:\projects\openmw\deps\OSG-3.4.0-scrawl-msvc2015-win64.7z
     - C:\projects\openmw\deps\ffmpeg-3.0.1-dev-win32.7z