Accept UTF-8 as encoding case-insensitively
Remove unnecessary module loads
Switch to ExtUtils::MakeMaker

Try to keep the dependencies down, as this module may be used in modules
that need that.
Fix performance issue on 5.20.0

In hope this will be fixed in 5.20.1
Add various comments and minor fixups
Rename File::Slurp::Sane to File::Slurper
Improve benchmarks
v0.002

          rename File::Slurp::Sane to File::Slurper
          Accept UTF-8 as encoding case-insensitively
          Fix performance issue on 5.20.0