init submodules for appveyor

.editorconfig

@@ -8,5 +8,5 @@ indent_style = space
 insert_final_newline = true
 trim_trailing_whitespace = true
 
-[*.{h,hh,hpp,c,cc,cpp,cxx}]
+[*.{h,hh,hpp,c,cc,cpp,cxx,yml}]
 indent_size = 2

appveyor.yml

@@ -1,5 +1,8 @@
 image: Visual Studio 2017
 
+init:
+  - cmd: git submodule update --init --recursive
+
 build_script:
   - cmd: mkdir tmp
   - cmd: cd tmp