C++ syntax out of date

[jdlugosz]

Note that the current standard came out at the end of last year, and compilers are live-at-head for new features being standardized for C++20.

for (uint8_t mask= 0b1000'0000; mask; mask>>=1) {
Ref: C++17 §5.13.2

I noticed in particular that using separators in numeric literals breaks the coloring.