Add windows formatting script

Done in batch script because Powershell requires execution policy to be
changed to run scripts. Therefore batch files are considered to have a
lower barrier for entry.

build_scripts/win/format.cmd

@@ -0,0 +1,60 @@
+@echo off
+REM Echo off to avoid spam.
+
+REM Non zero is failure, 0 is success.
+SET exit_code_success=0
+SET exit_code_failure_build_apps=1
+SET exit_code_failure_build_locations=2
+
+REM Used for echos.
+SET current_activity=FORMAT
+
+REM If scripts are chain called the original dirs should not be overwritten.
+IF NOT DEFINED original_dir (
+    SET original_dir=%CD%
+)
+IF NOT DEFINED project_dir (
+    REM Arg 0 (called %0) is the full path to the file.
+    REM https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/call#batch-parameters
+    REM As per above link, %~dp0 expands the zeroth arg to a drive letter and path only.
+    REM Project dir is up two dirs from the file.
+    SET project_dir=%~dp0\..\..\
+)
+
+ECHO %current_activity%: Testing if clang-format can be located:
+
+IF NOT DEFINED CLANG_FORMAT_LOC (
+    ECHO %current_activity%: CLANG_FORMAT_LOC not defined. Using default value.
+    SET CLANG_FORMAT_LOC="C:\Program Files\LLVM\bin\clang-format.exe"
+)
+ECHO %current_activity%: CLANG_FORMAT_LOC set to '%CLANG_FORMAT_LOC%'.
+
+REM EXIST won't find items in the PATH. WHERE will.
+SET CLANG_FORMAT_VALID=0
+IF EXIST %CLANG_FORMAT_LOC% SET CLANG_FORMAT_VALID=1
+IF %CLANG_FORMAT_VALID% EQU 0 (
+    WHERE /Q %CLANG_FORMAT_LOC%
+    IF NOT ERRORLEVEL 1 SET CLANG_FORMAT_VALID=1
+)
+
+IF %CLANG_FORMAT_VALID% EQU 1 (
+    ECHO %current_activity%: CLANG_FORMAT_LOC exists.
+) ELSE (
+    ECHO %current_activity%: CLANG_FORMAT_LOC directory does not exist. Exiting.
+    EXIT /B %exit_code_failure_build_locations%
+)
+
+ECHO %current_activity%: Clang-format located.
+
+%CLANG_FORMAT_LOC% --version
+
+REM First iteration.
+FOR /R %project_dir%\src\ %%F IN (*.cpp *.h) DO (%CLANG_FORMAT_LOC% --style=file -i %%F & ECHO Iteration 1. %%F)
+
+REM Clang-format is sometimes indecisive about which exact rules to apply,
+REM leading to differences between first and second iteration. 
+REM Do it twice, just to be sure.
+
+FOR /R %project_dir%\src\ %%F IN (*.cpp *.h) DO (%CLANG_FORMAT_LOC% --style=file -i %%F & ECHO Iteration 2. %%F)
+
+ECHO %current_activity%: %current_activity% DONE.