v0.5.0

Fixes:

• fixed crash when reaching EOF while parsing a string when exceptions are disabled
• fixed some attribute warnings in GCC
• fixed build with GCC 8.2.0 (#15) (@shdnx)
• fixed exception mode detection sometimes being incorrect on MSVC
• fixed compilation on older implementations without std::launder
• fixed json_formatter type deduction on older compilers

Additions:

• added support for Unicode 13.0
• added support for \xHH escape sequences (toml/pull/796)
• added short-form license preamble to all source files
• added build configuration option for compiling examples