Release v4.0.0

• Modernize to use newer and better tools that are available across all platforms
• Switch to GitHub Actions for automated build on Windows, macOS, and Ubuntu
• Rewrite the build system in Modern CMake
• Improved CMake support for use as a library in your project
• Removed static build projects and Makefile
• Bug-fix in Format class, include string header
• Simplify copyright headers
• Apply clang-format project wide for consistent formatting