Wrote test for setting the last login
Actually execute statement
Test attribute loading and changing
Mark warnings as errors
Remove git leftovers from gitignore again

@bjorn was right... This is annoying.
Ran clang-modernize

This turns many NULL / 0 usages into nullptr, verbose for loops into the
new range loop and adds override statements.

Due to the autoformat in some cases badly formatted lines are now
idented correctly but other parts of the file are not.
Made filenames uppercase

This looks better and is easier to read.