Add .editorconfig to mostly do the right thing with formatting.

.editorconfig

diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..3ba2494
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,9 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+[*.py]
+indent_style = space
+indent_size = 2