Allow use of inferred variable type (var) in all projects except Core

.editorconfig

@@ -86,9 +86,9 @@ dotnet_style_readonly_field = true:warning
 #### C# Coding Conventions ####
 
 # var preferences
-csharp_style_var_elsewhere = false:warning
-csharp_style_var_for_built_in_types = false:warning
-csharp_style_var_when_type_is_apparent = true:suggestion
+csharp_style_var_elsewhere = true:warning
+csharp_style_var_for_built_in_types = false:suggestion
+csharp_style_var_when_type_is_apparent = true:warning
 
 # Pattern matching preferences
 csharp_style_pattern_matching_over_as_with_null_check = true:suggestion
@@ -351,3 +351,10 @@ dotnet_diagnostic.ca1707.severity = none
 
 # CA1014: Mark assemblies with CLSCompliant
 dotnet_diagnostic.ca1014.severity = none
+
+
+[Yubico.Core/src/**/*.cs]
+# var preferences
+csharp_style_var_elsewhere = false:warning
+csharp_style_var_for_built_in_types = false:warning
+csharp_style_var_when_type_is_apparent = true:warning