Remove deprecated std::binary_function inheritance for C++17 compatibility

[Victorcorcos]

Summary

• Necessary to make it work -> 🎯 Phase 2: Complete Equations-Parser WebAssembly Integration parsec-web#2
• Remove std::binary_function<TString, TString, bool> inheritance from SortByLength struct in parser/suSortPred.h
• Fixes C++17 compatibility issue where std::binary_function was removed from the standard
• Enables WebAssembly compilation which requires modern C++ standards
• Updates README.md with a muuuch better version of it

Details

The std::binary_function base class was deprecated in C++11 and removed in C++17. The SortByLength functor doesn't need this inheritance as it already provides the required operator() method. This change maintains full functionality while ensuring compatibility with C++17 and later standards, which is necessary for WebAssembly compilation.

Test plan

• Verify compilation succeeds with C++17
• Confirm WebAssembly build works
• Ensure existing functionality remains unchanged