editorconfig: added to repository

We've got a bunch of inconsistent tabs/spaces for indentation, let's try
to normalize that.

Signed-off-by: Steven Noonan <[email protected]>

Author: Steven Noonan

.editorconfig

@@ -0,0 +1,9 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+[CMakeLists.txt,*.{cpp,h}]
+indent_style = tab
+indent_size = 4