Add all subproject and use on-demand script for CPM.cmake

• adds an all directory, that builds all subproject (tests / standalone / documentation) in a single build
• uses the new script to download CPM.cmake on-demand, avoiding code bloat

Enable CMake formatting

Activates cmake-format by enabling Format.cmake's FORMAT_CHECK_CMAKE option and adds a default .cmake-format configuration file to the project.

Use m.css theme for Documentation

Documentation is now generated using the m.css Doxygen theme.

Doxygen and version header

• Automatic documentation generation via Doxygen
• Includes have been moved to include/greeter directory
• A version header containing a macro with the current version is automatically generated at <greeter/version.h>

Add Doxygen Support (beta 1)

This beta release is to test the automatic publishing workflow for the Doxygen documentation.

Fix tools and better windows support

• Tools are now only included for top-level projects and sanitisers should no longer cause linker errors
• Dependencies have been updated for better Windows support
• Github actions are restricted to the master branch and run for third-party pull requests

Better project support

• Update PackageProject.cmake to support autodetecting dependencies
• Update code coverage flags to include test implementation coverage to measure templates and header-only libraries
• Remove gcc-specific flags from standalone target

Tools.cmake and licence change

• Introduces a tools.cmake file to add support for sanitisers and ccache
• Change license to unlicence

Better MSVC support and test warnings

• /permissive- (standard compliance) flag has been added as a public flag for the library target on MSVC
• Tests are compiled with /W4 and /WX on MSVC
• Tests now also compile the main library target with warning flags enabled

v0.6: Add CONFIGURE_DEPENDS flag to globs and cleanup (#5)

* join comments

* join target properties

* add empty lines

* update readme

* add CONFIGURE_DEPENDS to glob sources

* update comment about glob

* update comment about removing unused files

* update glob comment in the main CMakeLists