project.clj: Add a compile alias

Signed-off-by: Gergely Nagy <algernon@balabit.hu>
Get rid of a few reflection warnings

Added a few type hints here and there, to get rid of a few reflection
warnings in places where they should not be any.

This partially addresses #12.

Signed-off-by: Gergely Nagy <algernon@balabit.hu>