in eq.lean, make rec_on depend on the proof, and add congruence theorems for n-ary functions with n between 2 and 5
in sigma.lean, finish proving equality of triples
in category.lean, define the functor category, and make the proofs of the arrow and slice categories easier for the elaborator
in eq, add theorem for proof irrelevance and congruence for binary functions
in sigma, add some support for triplets
in path, comment out two unneccesary definitions
in category, add Cat, slice, coslice, product and arrow categories, also add fully bundled approach
