Add .editorconfig and related GH Action

Signed-off-by: DL6ER <dl6er@dl6er.de>

.editorconfig

@@ -0,0 +1,40 @@
+# EditorConfig is awesome: https://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+[{.github/**,.devcontainer/**}]
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+charset = utf-8
+trim_trailing_whitespace = true
+
+[**/CMakeLists.txt]
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+charset = utf-8
+trim_trailing_whitespace = true
+
+[src/**]
+end_of_line = lf
+insert_final_newline = true
+indent_style = tab
+indent_size = tab
+tab_width = 8
+charset = utf-8
+trim_trailing_whitespace = true
+# The left part of the curly bracket should be on the next line
+curly_bracket_next_line = true
+spaces_around_operators = true
+spaces_around_brackets = none
+indent_brace_style = Allman
+
+[src/dnsmasq/**]
+indent_style = space
+indent_size = 2
+insert_final_newline = false
+trim_trailing_whitespace = false

.github/workflows/editorconfig.yml

@@ -0,0 +1,12 @@
+name: EditorConfig Checker
+
+on:
+  push:
+
+jobs:
+  editorconfig:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v2
+      - uses: editorconfig-checker/action-editorconfig-checker@main
+      - run: editorconfig-checker