Enable all features of Modern Perl with one import

Import the Modern::Perl module, which enables all features of Modern
Perl. It will in turn import strict and warnings, and eliminates the
need for us to explicitly import them.

This effectively sets the minimum required version of Perl to 5.10.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>
Use say instead of print

The say function introduced in Perl 5.10 works like print but implicitly
appends a newline character.

Signed-off-by: Marcus Karlsson <mk@acc.umu.se>