Adding hw04
Adding hash.c
Adding lecture12
Adding check_uniform
Adding lecture13
Adding solution
Adding Sync.py
Quick fix
Adding lecture 14
Log2 scale
Bug fix in Sync.py
Adding lecture15
Adding hw04 soln
Adding code for quiz 4
Adding list2_soln.c
Adding lecture18
Adding lecture19
Adding mutex example
Fixing matrix_soln.c
Merge branch 'master' of https://github.com/AllenDowney/SoftwareSystems