-Removed FuncRef, since Callable makes it obsolete -Removed int_types.h as its obsolete in c++11+ -Changed color names code
Using clang-tidy's `readability-braces-around-statements`. https://clang.llvm.org/extra/clang-tidy/checks/readability-braces-around-statements.html
Using clang-tidy's `modernize-use-nullptr`. https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-nullptr.html