fixed bug! circle-circle and rect-rect collisions kind of work now
problem: should have filtered self-bodies out of state so they wouldn't
have been compared against themselves, causing weird reversals
debugging code left in this commit for posterity. yay for Debug.Trace
cleaned up. note to self: use good, thorough, pre-written tests. wouldn't have caught this otherwise. also convert tuples to records (thanks O for all the help :-])
fixed syntax errors
starting refactor: tuples to records, standardize names
finished refactoring to use records instead of tuples. still inelegant
also added mass, acceleration, attachment, and environment characteristics
note the large circle as platform :)