Support externally generated files in .gitignore

We do this by including .gitignore-base in our generated .gitignore,
if the former exists.
Add Presentation.pdf
hlint police
oops: overpar rm did not work
execution log prints: remove prints for empty stdouts
Inline 'opts' into execParser
verbosity levels: add to opts and remove log prints accordingly
Merge pull request #5 from renanafr/master

Execution log : add verbosity levels, remove default prints for empty stdouts
Oops: --version needs to get the version at compile-time
buildsome.cabal: can build with template-haskell == 2.8 too