MSVC 2019 generates too many warnings and errors

[al-martyn1]

• peg_parser\interpreter.h(126): warning C4868: compiler may not enforce left-to-right evaluation order in braced initializer list
  peg_parser\interpreter.h(126): warning C4868: compiler may not enforce left-to-right evaluation order in braced initializer list

• functional(660,27): warning C4244: 'return': conversion from 'double' to '_Rx', possible loss of data
  calculator.cpp(45): message : see reference to function template instantiation 'std::function<R (const peg_parser::Interpreter<R,VariableMap &>::Expression &,VariableMap &)>::function<main::<lambda_4f4ba99ff83df776d958244c9f6cd413>,0>(_Fx)' being compiled
  numeric(34,26): warning C4244: '=': conversion from 'R' to '_Ty', possible loss of data
  functional(660,27): warning C4244: 'return': conversion from '_Ty' to '_Rx', possible loss of data
  calculator_visitor.cpp(37,55): warning C4244: '=': conversion from 'double' to 'float', possible loss of data
  calculator_visitor.cpp(37,55): warning C4244: '=': conversion from 'double' to 'float', possible loss of data

• calculator_sequental.cpp(29,57): warning C5219: implicit conversion from '_Ty' to 'R', possible loss of data
  calculator_sequental.cpp(37,57): warning C5219: implicit conversion from '_Ty' to 'R', possible loss of data

• multiple python_indentation.cpp(100,84): warning C4365: 'argument': conversion from 'size_t' to 'const __int64', signed/unsigned mismatch

• python_indentation.cpp(51,1): warning C4267: 'argument': conversion from 'size_t' to '_Ty', possible loss of data

Also, json_parser example generates long list of errors

Test project can be found at https://github.com/al-martyn1/PEGParserTests