final cleanup

- add CHANGES note
- update copyrights and license headers
- add -j to the make commands in .gitlab-ci.yml to take
  advantage of parallelization in the gitlab CI process
10 jobs for 91-parallel-tests in 22 minutes and 28 seconds (queued for 12 seconds)
Status Job ID Name Coverage
  Build
passed #1904
linux docker
build:debian:buster:i386

00:11:42

passed #1901
linux docker
build:debian:jessie:amd64

00:10:33

passed #1902
linux docker
build:debian:jessie:i386

00:10:34

passed #1905
linux docker
build:debian:sid:amd64

00:11:11

passed #1906
linux docker
build:debian:sid:i386

00:11:42

passed #1903
linux docker
build:debian:stretch:amd64

00:11:07

passed #1907
linux docker
build:ubuntu:trusty:amd64

00:12:14

passed #1908
linux docker
build:ubuntu:xenial:i386

00:12:33

 
  Test
passed #1909
linux docker
test:debian:sid:amd64

00:09:53

passed #1910
linux docker
test:debian:sid:i386

00:09:45