Millis() and rollover tutorial

Tutorials
15

Tried it on

  1. gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4)
  2. Apple LLVM version 9.0.0 (clang-900.0.38)
    Target: x86_64-apple-darwin16.7.0
  3. ARM GCC 541
  4. Particle cloud compiler

All results were same.