v0.1.0

Added

• Added Solve trait for implementing puzzle solvers
• Added run function for solving a puzzle
• Added raw method to Input for retrieving the raw input
• Added lines method to Input for iterating over the lines in the input
• Added manhattan_distance for computing the Manhattan distance between two points

Changed

• Changed the contents of Input to be private
• Changed CharCounts trait to use usizes instead of i32s