Add to script and tex file for assignment 2 question 2

Add plots to Matlab script and explanations in tex file for assignment 2
question 2. Parts 2f, 2g are incomplete. Move common commands for
plotting spectrum of system H into a separate function.
Split assignment 2 Matlab script into separate files

Create individual Matlab script files for each assignment problem.
Change high variance in input u and additive output noise n to 100 times
initial value.
Fix estimated coherence calcultion

Use definition of coherence as presented in lecture. Update responses to
question 2.
Fix estimates in 2f, 2g in assignment 2

Use section specific inputs for system simulation in sections 2f, 2g.
Add responses for sections 2f, 2g in assignment 2