Add configuration file for EditorConfig

Handles source and CMake files.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>

.editorconfig

@@ -0,0 +1,16 @@
+root = true
+
+[*]
+end_of_line = lf
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[{CMakeLists.txt,*.cmake}]
+indent_style = space
+indent_size = 2
+tab_width = 2
+
+[{*.c,*.h}]
+indent_style = tab
+indent_size = 8
+tab_width = 8