Version 1.8.0

Changed

• Switched to C++14 as minimum requirement. Modernised the code accordingly.
• Only the tests need the Protobuf library when building.
• Improve compatibility with various STL flavors.
• Change license formatting to get recognized by license scanning tools.
• Add lots of const in places where we can. Also fix some other issues reported by clang-tidy.
• Various other code cleanups.
• Modernize documentation config, CMake config and CI workflows.

Fixed

• basic_pbf_builder constructor can not be noexcept.