adding Unit #3 code snippets
adding HW3 files
remove a few unncessary files
updated hw#3 images to the sizes corresponding to the ones use for the IDE
adding large images for students to test and experiment
adding code for timing atomic functions
adding HW#4 files to the repo
adding student_func.cu
fixed minor error in main
adding slides to unit #3 and unit #4
Merge https://github.com/udacity/cs344 to bring in Unit 3 and 4