up to question 3-7
fixed invalid array_container contracts
clang-format
added binary_tree and beginnings of container test suite
container tests pass
added algorithm.h and math.h
partial implementation up to 3-14
sparse array template
moving on to chapter_4
added chapter 4
fixed object contract include path
added sparse_array implementation, binary_tree successor predecessor complete
fixed binary search to void **
added tests for many collections, hashtable implementation is broken
clang-format
fixed min max binary tree (used incorrect dictionary_min implementation)
template for remaining questions
fixed math and wrote 3-28 in c
partial heap implementation
fixed type.h