added .editorconfig, code formatting

.editorconfig

@@ -0,0 +1,7 @@
+[*]
+charset=utf-8
+end_of_line=lf
+trim_trailing_whitespace=false
+insert_final_newline=false
+indent_style=space
+indent_size=2

NuSave.Core/IPackageExtensions.cs

@@ -3,11 +3,11 @@
 
 namespace NuSave.Core
 {
-    public static class IPackageExtensions
+  public static class IPackageExtensions
+  {
+    public static string GetFileName(this IPackage package)
     {
-        public static string GetFileName(this IPackage package)
-        {
-            return $"{package.Id}.{package.Version}.nupkg".ToLower();
-        }
+      return $"{package.Id}.{package.Version}.nupkg".ToLower();
     }
-}
+  }
+}

NuSave.Core/MsBuildPackageRef.cs

@@ -1,8 +1,8 @@
 namespace NuSave.Core
 {
-    public class MsBuildPackageRef
-    {
-        public string Include { get; set; }
-        public string Version { get; set; }
-    }
-}
+  public class MsBuildPackageRef
+  {
+    public string Include { get; set; }
+    public string Version { get; set; }
+  }
+}