Added an .editorconfig file

This allows most IDEs and editors (with the proper plugin) to
automatically use the correct identation and line endings.

In short, you'll never ever have to worry about tabs or line breaks in your
code again. In additon, this won't have any effect on your other files or
projects, who'll continue to use your own global or custom settings.

There are plugins available for Microsoft Visual Studio, Notepad++, gedit, vim,
and many other popular editors and IDEs.

More information can be found on http://www.editorconfig.org/.

.editorconfig

@@ -0,0 +1,18 @@
+# Configuration file for EditorConfig
+# More information is available under http://EditorConfig.org
+
+# Ignore any other files further up in the file system
+root = true
+
+# Configuration for all files
+[*]
+# Enforce Unix style line endings (\n only)
+end_of_line = lf
+# Always end files with a blank line
+insert_final_newline = true
+# Force space characters for indentation
+indent_style = space
+# Always indent by 4 characters
+indent_size = 4
+# Remove whitespace characters at the end of line
+trim_trailing_whitespace = true