Gofmt code

strange decisions
Use go logging
Add threshold parameter
Implement pixel sorting + tests

Go's conventions seem so _weird_ compared to what I'm used to
(js/clojure/java). I don't want to dismiss them after ~5 hours of using
go, but the sorting them definitely seems worse than even java at first
glance, which can't be good for beginners. I'm willing to believe that
my previous java/C conventions are clouding my judgement for now,
though.
Implement main loop with dummy code

Slight refactoring too
Implement basic Disjoint Set datastructure
Implement almost working algorithm

Forgot about pixels from the same island, and the logic is hella messy.
Will fix later.
Compare peaks consistently with sorting
Fix stupid implementation of highest peak checking

Algorithm probably works now, need to output octave-readable stuff to
check against sample results
Add octave display script
Handle threshold command line parameter
Log progress to stderr