Don't use `ALL_CAPS` for enumerators

Reason

Avoid clashes with macros.

Example, bad

 // webcolors.h (third party header)
#define RED   0xFF0000
#define GREEN 0x00FF00
#define BLUE  0x0000FF

// productinfo.h
// The following define product subtypes based on color

enum class Product_info { RED, PURPLE, BLUE };   // syntax error

Enforcement

Flag ALL_CAPS enumerators.