added missile data folder to gitignore
renamed binary_tree to tree
renamed binary_tree_node to node
renamed MultipleTreeStrategy to MultipleTree
renamed optimal_missile_destruction_route to best_destruction_route
renamed missile_destruction_routes to destruction_routes
renamed spec
renamed missile_destruction_routes to destruction_routes
refactor to a more OO style
change FileInput to Input::File
change FileInput to Input::File
extract exceptions in their own files
change FileOutput to Output::File