Created coding-standard.py to check whitespace/formatting of plain text files (#981)

Created coding-standard.py to check whitespace/formatting of plain text files.

The Python script will check text files to make sure they don't have
any tab characters (except Makefiles) and they don't have trailing
whitespace. I made it smarter than the sample pre-commit hook: it
*only checks the files that are being changed*, not the entire
repo. This way there's no huge commit just to update whitespace.

It's also able to do double duty as a PR check. Same thing, it only
checks the files in the PR, not the entire repo. If there's any bad
whitespace then it blocks the PR from being committed.

I've *also* added checking of the C formatting to the
tool. **HOWEVER** it will only check the C++ coding style **IFF** the
previous version of the file in the repo *already* conforms to the
standard as specified by the `.clang-format` file. I suspect there
aren't many files that already conform, if there are any at all, so
it's unlikely anyone will run into complaints about an edited file not
having proper formatting. A brand new file *will* be expected to
conform though. I made a couple of minor changes to the
`.clang-format`: no tab characters, and lines should be less than 96
characters long.

Two other features are `--fix` which will automatically make the
necessary corrections to only the files listed on the command line;
and `--show` that reformats the specified file and prints it to
stdout.

Author: FozzTexx

.clang-format

@@ -1,12 +1,11 @@
 BasedOnStyle: LLVM
-ColumnLimit: 200
+ColumnLimit: 95
 AllowShortBlocksOnASingleLine: true
 AlwaysBreakAfterReturnType: None
 IncludeBlocks: Preserve
 SortIncludes: false
-UseTab: Always
 IndentWidth: 4
-TabWidth: 4
+UseTab: Never
 AccessModifierOffset: -4
 AlignConsecutiveMacros: true
 AlwaysBreakTemplateDeclarations: Yes
@@ -28,4 +27,5 @@ BraceWrapping:
   BeforeWhile: false
   SplitEmptyRecord: false
   SplitEmptyNamespace: false
-IndentPPDirectives: None
+IndentPPDirectives: None
+ReflowComments: true

.dir-locals.el

@@ -0,0 +1,4 @@
+((c++-mode . ((indent-tabs-mode . nil)
+              (c-basic-offset . 4)
+              (c-file-offsets . ((substatement-open . 0)))
+              )))

.github/workflows/check-formatting.yml

@@ -0,0 +1,25 @@
+name: Check Formatting
+
+on:
+  pull_request:
+
+jobs:
+  check-formatting:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0  # needed for diffing against base
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+
+      - name: Install your formatter
+        run: pip install -r .github/workflows/coding-standard-requirements.txt
+
+      - name: Run formatting check
+        run: ./coding-standard.py --against origin/${{ github.base_ref || 'master' }}
+

.github/workflows/coding-standard-requirements.txt

@@ -0,0 +1,2 @@
+pyyaml
+termcolor