v8.75

• fixes #138 - retain UTF-8 BOM on Save
• fixes #135 - ensure setting cell value works correctly with column headers offset
• fixes #132 - ignore c++ locale when mNumericLocale is set false
• fixes #129 - fix precision loss when writing floating-point values to csv document
• merged #127 - fix no_converter::what() accessability
• fixes #122 - update doc mentioning package managers vcpkg and conan
• merged #124 - add missing "const" qualifier to several functions in class Document