Add basic editorconfig file

.editorconfig:
Add basic editorconfig file that enforces tabs of indent size 4 on all
C and C++ files and Unix-style line feeds and a final newline on all
files.

Author: dvzrv

.editorconfig

@@ -0,0 +1,11 @@
+# EditorConfig: https://editorconfig.org
+
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+
+[*.{c,cc,cpp,h}]
+indent_style = tab
+indent_size = 4