Add basic editorconfig for enforcing style

.editorconfig

@@ -0,0 +1,17 @@
+[*]
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+charset = utf-8
+
+max_line_length = 79
+
+indent_style = space
+indent_size = 4
+
+[*.yml]
+indent_size = 2
+
+[*.feature]
+max_line_length = 9999
+

MANIFEST.in

@@ -25,6 +25,7 @@ recursive-exclude doc *.asciidoc
 include doc/qutebrowser.1.asciidoc
 prune tests
 prune qutebrowser/3rdparty
+exclude .editorconfig
 exclude pytest.ini
 exclude qutebrowser.rcc
 exclude .coveragerc