Added .editorconfig file

A pretty standard way of specifying project indentation and line
terminators across editors: http://editorconfig.org/

Set to 4 character space indentation, LF line terminator.

Author: Shay Rojansky

.editorconfig

@@ -0,0 +1,11 @@
+; Top-most EditorConfig file
+root = true
+
+; Unix-style newlines
+[*]
+end_of_line = LF
+
+; 4-column space indentation
+[*.cs]
+indent_style = space
+indent_size = 4