Add editorconfig to configure indentation

Patch adds a commit 'Add editorconfig to configure indents'
(886976a) that was implemented and the
reverted in scope of issue with discard v2.

Follows up #90
Part of #134

.editorconfig

@@ -0,0 +1,23 @@
+# top-most EditorConfig file
+root = true
+
+# Unix-style newlines with a newline ending every file
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+[CMakeLists.txt]
+indent_style = space
+indent_size = 4
+
+[*.cmake]
+indent_style = space
+indent_size = 4
+
+[*.lua]
+indent_style = space
+indent_size = 4
+
+[*.{h,c,cc}]
+indent_style = tab
+tab_width = 8