Add editorconfig

Author: zvirja

.editorconfig

@@ -0,0 +1,16 @@
+root = true
+
+[*.{cs,fs,fsx}]
+indent_size = 4
+indent_style = space
+
+[*.{sln,csproj,fsproj,config,xml}]
+indent_size = 2
+indent_style = space
+
+[*.cs]
+# Require "this." keyword qualification in code
+dotnet_style_qualification_for_field = true:suggestion
+dotnet_style_qualification_for_property = true:suggestion
+dotnet_style_qualification_for_method = true:suggestion
+dotnet_style_qualification_for_event = true:suggestion