Add EditorConfig

Details at http://editorconfig.org/.

.editorconfig

@@ -0,0 +1,32 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+trim_trailing_whitespace = true
+
+[*.{c,cpp,h}]
+indent_style = space
+insert_final_newline = true
+max_line_length = 100
+
+[{CMakeLists.txt,*.cmake}]
+indent_style = tab
+
+[.editorconfig]
+insert_final_newline = true
+
+[*.gradle]
+indent_size = 4
+indent_style = space
+insert_final_newline = false
+
+[*.java]
+indent_style = tab
+insert_final_newline = true
+
+[*.xml]
+indent_size = 4
+indent_style = space
+insert_final_newline = true