Requirements for the midterm take-home portion

We have to refactor the given code and add functionality.
Initial commit!
Seprated listapp.h into slist.h/cpp
Removed listapp.h
Added deep copy constructor and destructor

Destructor frees memory used by node
Changed include file to slist.h
Copy constructor now copies all source properties
Now causes fatal_err if unable to add node; comments

properly iterates through source list when copying
Demonstrates copy constructor
Comments and white space
Updated requirements made these obsolete
Renamed slist.h; removed test for copy constructor
Updated documentation to reflect listapp.h change
Style changes
Style changes; fixed memory leak on add_node failure
Fixed deletion of uninitialized memory